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Modified )/( GG -Expansion Methods for Soliton
Solutions of Nonlinear Differential Equations
By
Muhammad Shakeel
10-PhD-MT-03
PhD Thesis
In
Mathematics
HITEC University Taxila
Taxila, Pakistan
2015
ii
HITEC University Taxila
Modified )/( GG -Expansion Methods for Soliton Solutions of Nonlinear Differential Equations
A Thesis Presented to
HITEC University Taxila
In partial fulfillment
of the requirements for the degree of
PhD Mathematics
By
Muhammad Shakeel
10-PhD-MT-03
2015
iii
Modified )/( GG -Expansion Methods for Soliton Solutions of Nonlinear Differential Equations
A thesis submitted to the Department of Mathematics as partial fulfillment of the requirements for the award of Degree of PhD Mathematics.
Name Registration Number
Muhammad Shakeel
10-PhD-MT-03
Supervisor
Prof. Dr. Syed Tauseef Mohyud-Din Department of Mathematics HITEC University Taxila
iv
HITEC University Taxila
The thesis titled Modified )/( GG -Expansion Methods for Soliton Solutions of Nonlinear
Differential Equations
submitted by
Muhammad Shakeel
Reg. No. 10-PhD-MT-03
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY IN MATHEMATICS
has been approved
External Examiner : _____________________________ Prof. Dr. Muhammad Ozair Ahmad
Department of Mathematics University of Engineering & Technology, Lahore
Supervisor : __________________________
Prof. Dr. Syed Tauseef Mohyud-Din Department of Mathematics HITEC University Taxila
Chairperson : __________________________ Prof. Dr. Muhammad Tahir Department of Mathematics HITEC University Taxila
Dean Faculty of Sciences: __________________________ Prof. Dr. Syed Tauseef Mohyud-Din Department of Mathematics HITEC University Taxila
v
Declaration
I, Muhammad Shakeel, 10-PhD-MT-03 hereby affirm that I have produced the work
presented in this thesis, during the scheduled period of study. I also affirm that I have not
taken any material from any source except referred to and wherever due that amount of
plagiarism is within acceptable range. If a violation of HEC rules on research has
occurred in this thesis, I shall be liable to punishable action under the plagiarism rules of
the HEC.
Date: ___________________
Signature of student:
Muhammad Shakeel
10-PhD-MT-03
vi
Certificate
It is certified that Mr. Muhammad Shakeel, registration number 10-PhD-MT-03 has
carried out all the work related to this thesis under my supervision at the Department of
Mathematics, HITEC University Taxila, and the work fulfills the requirement for award
of PhD degree.
Date: ____________________
Supervisor:
_____________________________ Prof. Dr. Syed Tauseef Mohyud-Din Department of Mathematics HITEC University Taxila
Chairperson:
_____________________________
Prof. Dr. Muhammad Tahir Department of Mathematics HITEC University Taxila
vii
Dedicated
to
My beloved Parents & Wife for their prayers love and care
&
to
Ayesha & Hadi
viii
ACKNOWLEDGEMENTS
All praises be to Almighty Allah, The Creator of the entire universe and countless
Darood and Salaams to beloved Holy Prophet Hazrat Muhammad (Peace Be Upon Him),
for Whom this universe has been manifested. I thank to Almighty Allah, Whose blessings
bestowed upon me talented teachers, provided me sufficient opportunities and enabled
me to undertake and execute this research work.
My cordial appreciation goes to my affectionate, sincere, kind and most respected
supervisor Prof. Dr. Syed Tauseef Mohyud-Din, Dean Faculty of Sciences for so
patiently bearing and guiding me, invaluably suggesting and continuously encouraging
me with his precious contributions in completing this thesis. I am a l s o grateful for his
encouraging comments as well. If not for his invaluable advice and guidance, this thesis
would not have come to realization. He has been very kind in extending all possible help
to make this work a success. His ideologies and concepts have a remarkable impact on
my research contrivances. He genuinely facilitated me without which my objective would
not have been obtained. I have learnt a lot from his abilities.
I would also like to pay the most sincere gratitude to Vice Chancellor of HITEC
University, Brig (R) Qamar Zaman for the provision of research oriented and
encouraging environment coupled with the appropriate facilities. His sincere efforts to
streamline the system can be considered a role model. His personal interest in the subject
proved to be the real driving force and the essential inspiring factor behind the success of
this work. It was his dynamic and proactive approach that enabled me to learn
mathematics and do the research under the guidance of eminent mathematicians of
national and international repute.
I would like to pay sincere thanks to Chairman Department of Mathematics, Professor
Dr. Muhammad Tahir and all the faculty members for their moral support, kind
comments and confidence boosting attitude. Special thanks to Dr. Asif Waheed being
helpful, especially in early stages in Maple programming collaboration with my
supervisor and Dr. Saira Zainab,in compiling of the thesis. They always guided me
sincerely and honestly throughout my course work as well as research work. Sincere
thanks to Mr. Syed Adeel Akhtar Shah (Assistant Professor) and Ms. Nashrah Usmani for
ix
editing and improving the language.
Finally, I am also very thankful to Prof. Dr. S. Kamran Afaq, Chairman Department of
Mechanical Engineering and Prof. Dr. Jameel Ahmed Chairman Department of Electrical
Engineering, for providing well equipped computer lab facility for my research work.
Last but not the least; I would also pay sincere thanks to my parents and my wife, though
their long lasting prayers have opened new horizons for my success. I pay regards to my
caring and loving children Ayesha Shakeel and Abdul Hadi, my sister, my brothers and
my friends, whose sincere prayers, best wishes always make me courageous and daring
throughout my life.
Muhammad Shakeel
10-PhD-MT-03
x
ABSTRACT
Modified )/( GG -Expansion Methods for Soliton Solutions of
Nonlinear Differential Equations
Solitons play a pivotal role in many scientific and engineering phenomena. Solitons are a
special kind of nonlinear waves that are able to maintain their shape along the
promulgation. From the last four decades, the rampant part of fundamental phenomenon
of soliton has successfully attracted the researchers from the physical and mathematical
sciences. Various branches of science like solid-state physics, plasma physics, particle
physics, biological systems, Bose-Einstein-condensation and nonlinear optics are
enjoying the benefits taken from soliton. Soliton research gives way to theoretical aspects
such as soliton existence, computation of soliton profiles and soliton stability theory by
using the tools of soliton dynamics and soliton interactions to applicative aspects.
The hub of this thesis is to search not only for the solitary solutions of nonlinear
differential equations but also for nonlinear fractional differential equations. This piece of
writing targets to give an intuitive grasp for; Further Improved )/( GG -expansion,
Extended Tanh-function, Improved )/( GG -expansion, Alternative )/( GG -expansion
with generalized Riccati equation, )/1,/( GGG -expansion and Novel )/( GG -
expansion methods. Moreover, we shall extend Novel )/( GG -expansion method to
nonlinear fractional partial differential equations arising in mathematical physics. For
multifarious applications, all the methods are glib to follow. In addition, these methods
give birth to several types of the solutions like hyperbolic function solutions,
trigonometric function solutions and rational solutions. The premeditated methods are
very efficient, reliable and accurate in handling a huge number of nonlinear differential
equations.
xi
TABLE OF CONTENTS
Introduction---------------------------------------------------------------------------------1
1. Preliminary Definitions-------------------------------------------------------------------7
1.1. Introduction-------------------------------------------------------------------------8
1.2. Some Basic Definitions of Solitary Wave Theory-----------------------------8
1.2.1. Soliton----------------------------------------------------------------------8
1.2.2. Solitary Waves-------------------------------------------------------------8
1.2.3. Traveling Wave------------------------------------------------------------9
1.2.4. Types of Traveling Wave Solutions------------------------------------9
1.2.4.1. Solitary Waves and Solitons----------------------------------9
1.2.4.2. Kink Waves---------------------------------------------------10
1.2.4.3. Periodic Waves-----------------------------------------------11
1.2.4.4. Peakons--------------------------------------------------------11
1.2.4.5. Cuspons--------------------------------------------------------12
1.2.4.6. Compactons---------------------------------------------------12
1.3. Fractional Derivative-------------------------------------------------------------13
1.3.1. Riemann-Liouville Fractional Derivative ----------------------------13
1.3.2. Modified Riemann-Liouville Fractional Derivative ----------------13
1.4 Integrability Tests-----------------------------------------------------------------15
1.4.1. Conservation Laws------------------------------------------------------15
1.4.2. Lax Pair-------------------------------------------------------------------16
1.4.3. Generalized Symmetries------------------------------------------------16
1.5. Analysis of the Methods---------------------------------------------------------19
2. Exact Solutions of Nonlinear Differential Equations by Further Improved
)/( GG -Expansion and Extended Tanh-Function Methods--------------------36
2.1. Introduction---------------------------------------------------------------------------------37
2.2. Numerical Examples----------------------------------------------------------------------38
xii
2.2.1. The (3 + 1)-Dimensional Potential-YTSF Equation-------------------------38
2.2.2. The (3 +1)-Dimensional Jimbo-Miwa Equation------------------------------46
2.2.3. The (2 + 1)-Dimensional CBS Equation---------------------------------------55
2.2.4. The Benjamin-Bona-Mahony (BBM) Equation------------------------------63
2.2.5. The Symmetric Regularized Long Wave Equation--------------------------71
3. Soliton Solutions of Nonlinear Evolution Equations by Improved )/( GG -
Expansion Method-----------------------------------------------------------------------79
3.1. Introduction---------------------------------------------------------------------------------80
3.2. Numerical Examples----------------------------------------------------------------------81
3.2.1. The Burgers Equation------------------------------------------------------------81
3.2.2. The Zakharov-Kuznetsov (ZK) Equation-------------------------------------83
3.2.3. The Boussinesq Equation---------------- ---------------------------------------87
3.2.4. The Coupled Higgs Equations--------------------------------------------------89
3.2.5. The Maccari System--------------------------------------------------------------93
3.2.6. The Fifth Order Caudrey-Dodd-Gibbon Equation---------------------------96
4. Applications of Alternative )/( GG -Expansion Method with Generalized
Riccati Equation------------------------------------------------------------------------102
4.1. Introduction-------------------------------------------------------------------------------103
4.2. Numerical Examples---------------------------------------------------------------------104
4.2.1. The (1 + 1)-Dimensional Kaup-Kupershmidt Equation--------------------104
4.2.2. The Sixth-Order Boussinesq Equation ---------------------------------------111
4.2.3. The Fifth Order CDGSK Equation-------------------------------------------116
4.2.4. The (3 + 1)-Dimensional Modified KdV-ZK Equation--------------------122
5. Traveling Wave Solutions of Nonlinear Partial Differential Equations by
)/1,/( GGG -Expansion Method--------------------------------------------------128
5.1. Introduction-------------------------------------------------------------------------------129
5.2. Numerical Examples---------------------------------------------------------------------130
5.2.1. The Positive Gardner-KP Equation-------------------------------------------130
5.2.2. The (2 + 1)-Dimensional CBS Equation-------------------------------------138
5.2.3. The Modified Benjamin-Bona-Mahony Equation--------------------------142
xiii
6. Applications of Novel )/( GG -Expansion Method to Nonlinear Evolution
Equations---------------------------------------------------------------------------------150
6.1. Introduction-------------------------------------------------------------------------------151
6.2. Numerical Examples---------------------------------------------------------------------151
6.2.1. The ZK-BBM Equation--------------------------------------------------------152
6.2.2. The Symmetric Regularized Long Wave Equation-------------------------168
6.2.3. The Boussinesq System--------------------------------------------------------184
6.2.4. The (3 + 1)-Dimensional Burgers Equations--------------------------------201
6.2.5. The (3 + 1)-Dimensional Modified KdV-ZK Equation--------------------208
7. Novel )/( GG -Expansion Method for Fractional Partial Differential
Equations---------------------------------------------------------------------------------219
7.1. Introduction-------------------------------------------------------------------------------220
7.2. Numerical Examples---------------------------------------------------------------------221
7.2.1. The Time Fractional Simplified MCH Equation----------------------------221
7.2.2. The Time Fractional BBM-Burgers Equation-------------------------------234
7.2.3. The Space-Time Fractional SRLW Equation--------------------------------247
8. Conclusion--------------------------------------------------------------------------------263
9. References---------------------------------------------------------------------------------265
xiv
LIST OF TABLES
Table 1.1. The general representation of solutions of Eq. (1.11)--------------20
xv
LIST OF ABBRIVATIONS
YTSF Yu-Toda-Sasa-Fukuyama
CBS Calogero-Bogoyavlenskii-Schiff
BBM Benjamin-Bona-Mahony
SRLW Symmetric Regularized Long Wave
NLEEs Nonlinear Evolution Equations
ODE Ordinary Differential Equation
PDE Partial Differential Equation
KdV Korteweg-de Vries
ZK Zakharov-Kuznetsov
CDG Caudrey-Dodd-Gibbon
CDGSK Caudrey-Dodd-Gibbon-Sawada-Kotera
MKdV Modified Korteweg-de Vries
KP Kadomtsev-Petviashvili
MBBM Modified Benjamin-Bona-Mahony
MCH Modified Camassa-Holm
xvi
LIST OF FIGURES
Fig. 1.1: General representation of Solitary Waves----------------------------------------------9
Fig. 1.2: Traveling Waves---------------------------------------------------------------------------9
Fig. 1.3: General representation of Solitons-----------------------------------------------------10
Fig. 1.4: General representation of Kink solution ---------------------------------------------10
Fig. 1.5: General representation of Periodic solution -----------------------------------------11
Fig. 1.6: General representation of Peakon solution-------------------------------------------11
Fig. 1.7: General representation of Cuspons----------------------------------------------------12
Fig. 1.8: General representation of Compacton ------------------------------------------------13
Fig. 2.1: Kink type solution of (2.37) for .0,0,2,1 0 zyp ---------------------------48
Fig. 2.2: Exact Kink solution of (2.38) for ,2,1 0 p .0,0 zy --------------------49
Fig. 2.3: Exact periodic traveling wave of (2.39) for ,0,1 0 p .0,0 zy ---------50
Fig. 2.4: Exact Kink solution of (2.43) for ,1,4/1 0 p .0,0 zy -------------------52
Fig. 2.5: Single soliton solution of (2.47) for ,3,2 0 p .0,0 zy -----------------53
Fig. 3.1: Singular soliton solution of (3.75) for .1,1,1 CBA ---------------------------99
Fig. 3.2: Bell-shaped 2sec h solitary wave solution of (3.76) for .1,1,1 CBA -------99
Fig. 3.3: Exact periodic wave solution of (3.77) for .2,1,1 CBA -------------------100
Fig. 3.4: Soliton solution of (3.78) for .2,1,1 CBA -----------------------------------100
Fig. 4.1: Solitons corresponding to solution 1u for .2,1,1 rqp ---------------------106
Fig. 4.2: Solitons corresponding to solution 20u for .2,1,3 rqp ------------------109
Fig. 4.3: Kink-type solution of 26u for .0,2,2 rqp -----------------------------------110
Fig. 4.4: Soliton solution of 27u for .0,3,0 rqp ----------------------------------110
Fig. 4.5: Solitons corresponding to solution 13u for .1,2,3 rqp -----------------114
Fig. 4.6: Singular soliton solution to solution 27u for .0,1,0 rqp ---------------116
Fig. 4.7: Solitons corresponding to solution 1u for .1,1,1 rqp ----------------------118
Fig. 4.9: Singular soliton solution of 14u for .1,2,3 rqp -------------------------------120
xvii
Fig. 4.10: Soliton solution of 27u for .0,2,0 rqp -------------------------------------122
Fig. 4.11: Exact periodic traveling wave solution of 1u for .9,2,1,1 rqp --123
Fig. 4.12: Soliton solution of 13u for .4,1,3,4 rqp -------------------------------125
Fig. 5.1: Soliton solution of 11u for .,1 xy ---------------------------------------------132
Fig. 5.2: Soliton solution of 21u for .,1 xy ---------------------------------------------133
Fig. 5.3: Soliton solution of 12u for .,1 xy ---------------------------------------------134
Fig. 5.4: Soliton solution of 23u for .,2 xy --------------------------------------------136
Fig. 5.5: Soliton solution of 23u for .,2 xy --------------------------------------------137
Fig. 5.6: Exact kink-type solution of 11u for .0,1,0,1 0 zk --------------------140
Fig. 5.7: Singular Kink solution of 21u for .0,1,0,1 0 zk ------------------------141
Fig. 5.8: Periodic traveling wave solution of 12u for ,0,1 0 .1,,1 wxzk ---142
Fig. 5.9: Soliton solution of 11u for .1 ----------------------------------------------------144
Fig. 5.10: Kink-type solution of 12u for .1 ----------------------------------------------145
Fig. 5.11: Soliton solution of 13u for .1 --------------------------------------------------147
Fig. 5.12: Periodic traveling wave solution of 23u for .2 --------------------------------147
Fig. 5.13: Periodic traveling wave solution of 14u for .1 --------------------------------148
Fig. 6.1: Graph of cuspon for 11u for .1,1,3,1,2,1,1 VbakCBA ---------155
Fig. 6.2: Singular soliton solution for 21u for .1,1,1,1,2,1,1 VbakCBA ---155
Fig. 6.3: Soliton solution for 91u for ,2,1,1 CBA .1,1,3,1 Vbak ------158
Fig. 6.4: Periodic solution for 121u for ,2,1,1 CBA .1,1,3,1 Vbak ----159
Fig. 6.5: Singular periodic solution for 131u for .1,1,3,2,2,1,1 VbakCBA ---160
Fig. 6.6: Singular periodic solution for 123u for .1,1,3,2,2,1,1 VbakCBA ---167
Fig. 6.7: Graph of cuspon for 11u for .1,1,2,1,1 VkCBA ----------------------171
Fig. 6.8: Singular soliton solution for 21u for ,2,1,1 CBA .1,1 Vk ------------171
Fig. 6.9: Soliton solution for 91u for ,2,1,1 CBA .1,1 Vk ----------------------174
xviii
Fig. 6.10: Periodic solution for 121u for ,2,1,1 CBA .1,1 Vk --------------------175
Fig. 6.11: Bell-shaped 2sech solution for 231u for .1,1,2,0,1 VkCBA -------178
Fig. 6.12: Periodic wave solution for 122u for ,2,1,1 CBA .1,2 Vk ----------181
Fig. 6.13: Singular periodic solution for 123u for .1,2,1,1 VCBA ------------------183
Fig. 6.14: Graph of cuspon for 11u for .1,1,1,1,2,1,1 VbakCBA --------187
Fig. 6.15: Soliton solution for 91u for ,2,1,1 CBA .1,3,1,1 Vbak -----190
Fig. 6.16: Periodic traveling wave solution for 121u for ,2,1,1 CBA ,2k
,1a .1,3 Vb ----------------------------------------------------------------191
Fig. 6.17: Bell-shaped 2sech solution for 231u for .1,3,1,1,2,0,1 VbakCBA --194
Fig. 6.18: Periodic traveling wave solution for 132u for ,2,1,1 CBA ,1k
.1,5,1 Vba ------------------------------------------------------------------197
Fig. 6.19: Singular periodic solution for 123u for .1,3,1,2,1,1 VbaCBA --199
Fig. 6.20: Kink-type solution of 11u for ,2,1,1 CBA ,1,1,1,1 cbak
.,10 zyx ----------------------------------------------------------------------203
Fig. 6.21: Periodic traveling wave solution for 121u for ,1,1,2,1,1 akCBA
,1,1 cb .,10 zyx -------------------------------------------------------204
Fig. 6.22: Soliton solution of 21u for ,0,9,2,5.0,1,3 ykCBA .0z ----210
Fig. 6.23: Exact periodic traveling wave solution of 121u for ,5.1,2 BA ,0C
.0,0,9,2 zyk ------------------------------------------------------------212
Fig. 6.24: Soliton solution of 131u for ,0,9,2,5.0,5.1,2 ykCBA .0z ---212
Fig. 6.25: Periodic traveling wave solution of 122u for ,5.1,2 BA ,0C ,9,1 k
.0,0 zy ----------------------------------------------------------------------------214
Fig. 6.26: Kink solution of 14u for ,2,5.1,1 CBA .0,0,9,1 zyk -------216
Fig. 6.27: Periodic traveling wave solution of 124u for ,2,1,1 CBA ,9,2 k
.0,0 zy -------------------------------------------------------------------------------217
Fig.7.1 (a - d): Exact kink solution of 11u for .1,1,1,1,2,1,1 LkCBA --224
xix
Fig.7.2 (a-d): Singular kink solution of 21u for .5,1,1,2,1,2,5 LkCBA ---225
Fig.7.3 (a -d): Periodic traveling wave solution of 122u for
.12,1,1,2,2,1,2 LkCBA --230
Fig.7.4 (a -d): Singular periodic traveling wave solution of 123u for ,2,2,1,1 kCBA
.9,1,1 L -----------------------------------------------------------------------------------232
Fig.7.5 (a-d): Singular soliton solution of 21u for .1,1,1,2,1,1 VLkCBA --237
Fig.7.6 (a-d): Bell-shaped 2sec h solution of 231u for .1,1,1,2,0,1 VLkCBA ----242
Fig.7.7 (a-d): Periodic traveling wave solution of 123u for ,2,2,1,2 kCBA
.1,1 VL ------------------------------------------------------------------------------------------246
Fig.7.8 (a, b): Bell-shaped 2sec h solution of 231u for .1,1,1,2,0,1 VLkCBA ---255
Fig.7.9 (a, b): Periodic traveling wave solution of 122u for ,1,2,1,2 kCBA
.1,1 VL -----------------------------------------------------------------------------------------258
Fig.7.10 (a, b): Singular periodic solution of 123u for .1,1,2,1,1 VLCBA ---261
1
Introduction
It is illustrious that nonlinear evolution equations are big wheel in expanding significant
dynamic behaviors in fluid physics, solid physics, elementary particle physics, biological
physics, chemistry and superconductor physics etc., the probing of the exact solutions to
nonlinear evolution equations can help us analyzing and understanding their manifold
dynamical properties. The presented piece of writing is quite a fascinating research topic
that how to solve riddle partial differential equations particularly cops grabbing solutions,
including traveling wave solutions and soliton solutions and the topic also mesmeric for
Mathematicians, Physicists and Dynamicists. The delving of solitary wave solutions for
the nonlinear equations performs a seminal part in many scientific and engineering areas
such as plasma physics, solid state physics, fluid mechanics, chemistry and many others.
Soliton was first unveiled in 1834 by the Scottish naval engineer John Scott Russell
[191], who heeded that a canal boat stopping suddenly gave rise to a solitary wave which
traveled down the canal for several miles, without breaking up or losing strength. Russell
clepes this phenomenon the “soliton.” Russell adduced an enthralling historical account
the weighty scientific observation as well as fetching article as:
“I was observing the motion of a boat which was rapidly drawn along a narrow channel
by a pair of horses, when the boat suddenly stopped-not so the mass of water in the
channel which it had put in motion; it accumulated round the prow of the vessel in a state
of violent agitation, then suddenly leaving it behind, rolled forward with great velocity,
assuming the form of a large solitary elevation, a rounded, smooth and well-defined heap
of water, which continued its course along the channel apparently without change of form
or diminution of speed. I followed it on horseback, and overtook it still rolling on at a rate
of some eight or nine miles an hour, preserving its original figure some thirty feet long
and a foot to a foot and a half in height. Its height gradually diminished, and after a chase
of one or two miles I lost it in the windings of the channel. Such, in the month of August
1834, was my first chance interview with that singular and beautiful phenomenon which I
have called the Wave of Translation”.
Russell catching ideas got failed until 1965, when Zabusky and Kruskal [260] began to
use a finite difference approach to the study of KdV equation, which was procured by
Korteweg and de Vires [110]. Several analytical methods also led to a complete
2
apprehending of solitons, remarkably the inverse scattering transform proposed by
Gardner et al. [64] in 1967. The magnitude of Russell’s discovery was then fully
acknowledged. It was unmasked that mathematical and physical theory of “soliton”
paved the way to describe many phenomena in physics, electronics, and biology. A
historical account of the scientific development of solitons is found in [70, 76].
In the recent past nonlinear sciences have touched the summit of unparalleled
development and progress and in the similar context wide range of analytical, semi
analytical and numerical schemes have been developed to handle the complexity of
diversified physical problems. Most of the developed techniques have their limitations
tied with some inbuilt deficiencies including limited convergence, divergent results,
linearization, discretization, unrealistic assumptions, huge computational work and non-
compatibility with the versatility of physical problems. Exact traveling wave solutions of
KdV, mKdV, variant Boussinesq and Hirota-Satsuma equations were obtained recently
by Wang et al. [217], when they presented a reliable technique naming )/( GG -
expansion method. In this technique, second order linear ordinary differential equation
with constant coefficients is utilized as an auxiliary equation
.0)()()( GGG
Consequently, this work has been used to procure exact traveling wave solutions for the
nonlinear differential equations in mathematical physics [35, 39, 61, 65, 108, 125, 177,
186, 239]. Efficiency and convenience of the proposed algorithm is paid heed as it has
lesser computational work as compared to some existing schemes including, Exp-
Function [15, 37, 71, 136, 144, 170, 174, 180, 181, 253], Modified Exp-Function [211],
Tanh-Function [151-153, 208-210, 225, 226], F-Expansion [16, 33, 212, 215, 273], Sine-
Cosine [218, 224], Hirota Bilinear Transformation [84, 124, 143, 150, 277], Bäcklund
Transformation [88, 129, 147], Inverse Scattering Transform [19, 122], Adomian’s
Decomposition [1, 2, 5, 21, 22, 32, 47, 48, 50, 52, 94, 97, 99, 101, 102, 185, 203, 237],
Variational Iteration [3, 9, 13, 14, 53, 66, 78, 85, 176, 205, 234, 240, 242, 257],
Homotopy Perturbation [4, 8, 46, 73, 75, 109, 166, 256, 258], Homotopy Analysis [6, 10-
12, 49, 51, 118-121, 165, 251 ], Extended Transformed Rational Function [270], Sech-
Function [145] and other methods [29, 62, 63, 86, 133, 137, 138, 140, 148, 149, 241, 243,
246, 271].
3
It is worth mentioning that Ma [139] presented a novel class of exact explicit solutions to
the Korteweg-de Vires equation using its bilinear form. Such solutions contain
singularities of trigonometric and exponential wave functions. The functions used in the
Wronskian determinants were derived from eigen functions of the Schrödinger spectral
problem associated with complex eigen values and the resulting solutions were termed as
the complexion solutions. In a subsequent work, Ma and Maruno [142] developed the
complexiton solutions for Toda lattice equation through the Casoratian formulation and
hence obtained a set of coupled conditions which guaranteed Casorati determinants to be
the solution of Toda Lattice which consequently produced complexiton solutions.
Moreover, Ma and You [135] used variation of parameters for solving the involved non-
homogeneous partial differential equations and obtained solution formulas helpful in
constructing the existing solutions coupled with a number of other new solutions
including rational solutions, solitons, positions, negatons, breathers, complextions and
interaction solutions of the KdV equations. In fact, the exp-function method is restricted
to produce rational solutions in the form of transformed variables and such solutions can
be obtained easily by making use of other techniques including Wronskian and
Casoratian [134]. Recently, Ma et al. [141] presented a much more general idea to yield
exact solutions to nonlinear wave equations by searching for the so-called Frobenius
transformations. Also the solutions of the Riccati equation (1.16) and the generalized
Riccati equation (1.33) and (1.57) are presented in 1996 by Ma and Fuchssteiner [130]
much earlier than [60] and [278]. Moreover, if G satisfies (1.24), then )/( GGF
solves a Riccati equation .2CFBFAF Therefore, )/( GG -expansion method is
basically the expansion approach around an integrable equation including a Riccati
equation, which is presented systematically in [130]. Moreover, a lot of research can be
made in future on the basis of presented work. For example, if complexiton solutions can
be added by making an appropriate use of multiple exp-function method presented by Ma
et al. [144].
In1999, Homotopy Perturbation method was first proposed by J. H. He [74] and applied
to nonlinear equations. This technique has been employed to solve a large diversity of
linear and nonlinear problems. Yildirim [254, 256, 258] applied homotopy perturbation
method to solve both linear and nonlinear boundary value problems for the space-and
4
time-fractional telegraph equations, the fourth-order integro-differential equations, time-
dependent Cauchy reaction-diffusion equation. Yildirim and Momani [252] also exploit
this technique to obtain analytical solutions to a fractional oscillator, which is obtained
from the analogous equation of motion of a determined harmonic oscillator by replacing
the second-order time derivative by a fractional derivative of order with .20
Yildirim [255] again applied this technique to obtain approximate solutions of nonlinear
differential-difference equations.
In 1994, George Adomian [21] was the first to initiate and urbanized the Adomian
decomposition method and applied it to solve the frontier problems of physics. Later on,
substantial amount of research work has been empowered by using this method to a broad
class of linear and nonlinear ODEs, PDEs and integral equations as well. Kaya [103-105]
implemented this technique to find exact, approximate and solitary wave solutions of the
compound KdV-type and compound KdV-Burgers-type, the generalized Boussinesq type
and generalized modified Boussinesq equations. Kaya and Inan [93] applied ADM to find
the solitary wave solutions of the combined KdV and MKdV equations. El-Sayed and
Kaya [54, 55] implemented the Adomian decomposition technique to unearth the solitary
wave solutions and numerical solutions of the seventh-order Sawada-Kotera and a Lax’s
seventh-order KdV and explicit traveling wave solutions of Whitham-Broer-Kaup
equations. Kaya and El-Sayed [98, 95] used this method for acquiring the soliton-like and
solitary wave solutions of the potential Kadomtsev-Petviashvili and the generalized
Burgers-Fisher equations.
Fractional calculus theory [189] has been applied to extensive class of intricate problems
arising in physics, biology, mechanics, visco-elasticity, applied mathematics and
nonlinear dynamics. Local fractional calculus is naked as one of constructive tools to deal
with everywhere continuous but nowhere differentiable functions in different areas of
science and engineering [31, 44, 238, 245-247]. Due to numerous applications of local
fractional calculus in different areas, it becomes a hot topic now a day and is successfully
applied to different problems by a number of genius researchers. For example, Yang et al.
[244] investigate a family of local fractional differential operators on Cantor sets for the
heat-conduction equation and the damped wave equation in fractal strings. Yang et al.
[240] applied local fractional variational iteration method for solving the local fractional
5
Laplace equations with the different fractal conditions.
To escalate the assortment of applicability, many researchers extend the basic )/( GG -
expansion method such as, a generalization of the original )/( GG -expansion method
was prearranged by Zhang et al. [275] for the evolution equations with erratic
coefficients. To endeavor general traveling wave solutions, the genius researcher, Zhang
et al. [272] also offered an enhanced )/( GG -expansion method. A spanking new method
of the )/( GG -expansion scheme was offered by Zayed [265] in which, G gratifies the
Jacobi elliptical equation .242cbGaGG Zayed [268] again throws light on a
further another approach of the basic )/( GG -expansion method in which G is the
solution of the Riccati equation )()( 2 GBAG .
Akbar et al. [24] purveyed further new solutions of nonlinear evolution equations by
using the generalized and improved )/( GG -expansion scheme.
It is crystal clear that most of the physical phenomenon are nonlinear in nature and hence
appropriate solutions of the same are highly significant. A dire need to search for new
solutions of nonlinear differential equations cannot be neglected. Modifications of
)/( GG -expansion methods and subsequent extension for construction of the soliton
solutions of nonlinear physical problems [27, 30, 39, 43, 123, 167, 188, 194-202, 216,
219, 220, 231, 232, 239] are proved to be brain wave of this work. Efficiency, accuracy
and user friendly factors of proposed modifications in )/( GG -expansion method are
highly observed. Computational work and subsequent numerical results are fully
supportive of the reliability of suggested schemes. The work in thesis is organized as
follows:
In Chapter 1, brief introduction of soliton theory and some definitions of fractional
derivatives are presented. Analysis of modified techniques including further improved
)/( GG -expansion, extended tanh, improved )/( GG -expansion, alternative )/( GG -
expansion with generalized Riccati equation, )/1,/( GGG -expansion, a novel )/( GG -
expansion scheme for integer order partial differential equations and for fractional-order
nonlinear evolution equations have been discussed.
Chapter 2 contains some new work on traveling wave solution of nonlinear partial
differential equations [123, 195, 196, 220, 239] via further improved )/( GG -expansion
6
and extended tanh-methods.
Chapter 3 discusses the traveling wave solutions of nonlinear evolution equations [39,
167, 197, 269] by using improved )/( GG -expansion method. Moreover, physical and
mathematical aspects of various nonlinear equations are researched by appropriate
graphs.
In Chapter 4, the soliton solutions of nonlinear evolution equations [43, 194, 198, 232]
are constructed by using the alternative )/( GG -expansion method in which, generalized
Riccati equation is used as an auxiliary equation. Moreover, this method is greatly
capable of reducing the size of computational work as compared to other existing
methods.
Chapter 5 comprises the applications of )/1,/( GGG -expansion method to seek the
exact solutions of nonlinear partial differential equations [30, 188, 200]. Efficiency and
accuracy of suggested scheme is highlighted by graphical representation.
Chapter 6 witnesses a novel )/( GG -expansion method for nonlinear differential
equations [199, 216, 219, 231, 232]. Various types of solutions including cuspons, bell
shaped ,sec 2h soliton, singular soliton, singular kink, periodic traveling wave, singular
periodic traveling wave have been obtained accordingly.
Chapter 7 is devoted to the study of fractional differential equations. A novel )/( GG -
expansion method is proposed to seek the soliton solutions of nonlinear fractional partial
differential equations [27, 201, 202]. Physical properties of several nonlinear traveling
wave solutions are examined by graphs which are obtained for various values of .
Conclusions are framed in Chapter 8, which shows that the applied/proposed modified
versions are highly accurate, user friendly, efficient and involves lesser computational
work as compared to number of existing techniques. It is to be highlighted that the
suggested algorithms are extremely simple but highly effective and may be extended to
other nonlinear problems of diversified physical nature.
Chapter 9 comprises all the references, which have been cited in this work.
7
Chapter 1
Preliminary Definitions
8
1.1 . Introduction
This chapter provides the basic concepts of solitary waves and fractional calculus. This
chapter not only discusses different terms like solitons and solitary waves, but also
explains these terms as the type of travelling wave solutions. It also includes the analysis
of some modified versions of the well-known direct computational )/( GG - expansion
methods. This section is subdivided into three sections. In the first section some basic
definitions of solitary wave theory are given. The basic definitions of fractional calculus
are given in second section and the third and last section discusses analysis of modified
techniques including:
o Further improved )/( GG -expansion method,
o Extended tanh-method,
o Improved )/( GG -expansion method,
o Alternative )/( GG -expansion method with generalized Riccati equation,
o )/1,/( GGG -expansion Method
o A novel )/( GG -expansion method and
o A novel )/( GG -expansion method for fractional-order NLEEs,
1.2. Some Basic Definitions of Solitary Wave Theory
1.2.1. Soliton
A soliton [221] is a solitary wave which preserves its shape and velocity upon nonlinear
interaction with other solitary waves. A Soliton has following properties;
1. It is of permanent form.
2. It is localized within a region.
3. It can interact with other solitons and emerge from the collision unchanged,
except for a phase shift.
4. Soliton is caused by an elusive balance between nonlinear and dispersive effects.
1.2.2. Solitary Waves
These waves have soliton-like solutions of nonlinear evolution equations, describing
wave process in dispersive and dissipation media [221]. A sketch of these types of waves
is shown below;
9
Fig. 1.1: General representation of solitary waves
1.2.3. Traveling Wave
Traveling wave [221] is defined as a wave in which the medium is traveling in the
direction of propagation of wave. Traveling waves arises in the study of nonlinear
differential equations, where waves are represented by the form;
,, Vtxftxu
Fig. 1.2: Traveling waves
and V is the speed of wave propagation. For ,0V the wave travels in the positive x
direction, whereas the wave moves in the negative x direction for .0V
1.2.4. Types of Traveling Wave Solutions
Traveling wave solutions are of many types and they are of particular importance in
solitary wave theory. Here, six different types of traveling wave solutions are
described with their figures.
1.2.4.1. Solitary Waves and Solitons
asymptotically zero at large distances. The particular types of solitary waves are
solitons. The soliton solution is a spatially confined solution, hence,
0)( ,)(),( uuu as ., Vtx
10
Fig. 1.3 : General representation of solitons
The KdV equation is a pioneer model for analytic bell-shaped 2sech solitary wave
solutions.
1.2.4.2. Kink Waves
Kink waves [221] are traveling waves, which ascend or descend from one asymptotic
state to another. The Kink solution comes close to a constant at infinity. The standard
dissipative burgers equation,
,xxxt vuuuu
is a well known equation that gives kink solutions, where v is the viscosity coefficient.
The graphical representation of Kink wave is
Fig. 1.4 : Shows the graph of a kink solution .tanh1, txtxu
11
1.2.4.3. Periodic Waves
Periodic waves [221] are traveling waves that are periodic such as )cos( tx . The
standard wave equation xxtt uu gives periodic solutions. Graphical representation is
given below;
Fig. 1.5 : General representation of periodic solution for .)cos( tx
1.2.4.4. Peakons
Peakons [221] are the solitary wave solutions. In this case the traveling solutions are
smooth except for a peak at the corner of its crest. The Peakons are solutions retaining
their shape and speed after interacting. Peakons were investigated and classified as
periodic peakons and peakons with exponential decay. Some graphical representations of
peakons are given below;
Fig. 1.6 : General representation of Peakon .,tx
etxu
12
1.2.4.5. Cuspons
Solitons are also found in the form of Cuspons [221], where solution demonstrates cusps
at their peaks. Unlike Peakons, where the derivative at the climax fluctuates only by a
sign, the derivative at the hop of Cuspons deviates. It is imperative that the Soliton
solution together with its derivatives approaches zero as .0x
Fig. 1.7: General representation of Cuspon .exp, 6
1
txtxu
1.2.4.6. Compactons
It is a new class of solitons with compact spatial support such that each compacton is a
soliton confined to a finite core. Compactons [221] have some properties, which can be
described in one of the following ways:
1. They are of finite wavelength with compact support.
3. They are free of exponential tail.
4. They are described by the absence of inestimable wings.
5. They are robust soliton-like solutions.
Graphical representation is given below;
13
Fig. 1.8 : General representation of Compacton
1.3. Fractional Derivative
1.3.1. Riemann-Liouville Fractional Derivative
The Riemann-Liouville fractional derivative [82] of order α for a function f is defined by
x n
n
n
x dssfsxdx
d
nxfD
0
1.
1
(1.1)
Note: The main disadvantage of Riemann-Liouville fractional derivative is that the
fractional derivative of a constant does not vanish. If ,Cf then
.1
CxCDx (1.2)
1.3.2. Modified Riemann-Liouville Fractional Derivative
The modified Riemann-Liouville [90, 91] derivative is defined as;
.1,1,
,10,01
10
nnntf
dfftdt
d
tfDnn
t
t
(1.3)
The modified Riemann-Liouville derivative has properties
,
1
1
ttDt (1.4)
,tgDtftfDtgtgtfD ttt (1.5)
. tgtgfDtgDtgftgfD gtgt
(1.6)
14
Definition 1.1 [228] The Euler constant is given by
.5772156649.0ln1
Lim1
n
kn
nk
Definition 1.2 [228] For Cz \ ,...3,2,1,0 Euler’s Gamma function z is
defined as
,...3,2,1,0,0zRe/1
0zRe,0
1
zifzz
ifdtetz
tz
Theorem 1.1 [228] Euler's Gamma function satisfies the following properties:
1. For ,0zRe the first part of definition (1.2) is equal to
1
0
11 .lnz dtz
t
2. For Cz \ ,...3,2,1,0
.1zz z
3. For n
.!1 nn
4. For Cz \ ,...3,2,1,0
.z-1z- z
5. For 0zRe the following limit holds:
nzzzz
nn z
n
...21
!Limz
6. Let Cz \ .,...3,2,1,0 Then Euler’s Gamma function can be defined by
1
z ,1z
1
n
nz
en
zze
where is the Euler constant.
7. Euler’s Gamma function is analytic for all Cz \ .,...3,2,1,0
8. Euler’s Gamma function is not at all zero.
9. For all non-integer ,Cz
15
z
sinz-1z and
z
sinz-z
10. For half-integer urging, Nnn ,2/ has the meticulous form
,
2
!!22/
2/1
n
nn
where !!n is the dual factorial defined by
1,01
02.4.6...2.
01.3.5...2.
!!
n
evennnn
oddnnn
n
Theorem 1.2 [228] Let ,0a and suppose that f and g are analytic on ., haha
Then
xgJxfDk
xgDxfDk
xfgDk
ka
k
k
ka
ka
10
(1.6a)
for .2/haxa
1.4. Integrability Tests [79]
From the last thirty years, the study of integrability of nonlinear ordinary and partial
differential equations has been the theme of most significant research developments. For
looking into the integrability of systems of partial differential equations, different
techniques are used; like conserved densities, Lax pair and generalized symmetries.
1.4.1 Conservation Laws [221]
For any differential equation, a conservation law is a divergence term
,0
x
X
t
TXDTD xt (1.6b)
where the quantities T and X are called density and flux respectively and none of them
engrosses derivatives with respect to t, is called a conservation law. Integration of (1.6b)
yields
TdxP Constant, (1.6c)
provided X disappears at .
16
1.4.2 Lax Pair [221]
If a partial differential equation can be written in Lax pair form
PLLPdt
dL (1.6d)
where, L and P are one-parameter operators from a fixed Hilbert space to itself and are
one time differentiable. Then the given partial differential equation generally has an
unlimited number of first integrals, which assist to study it.
1.4.3 Generalized Symmetries [79]
A vector function of the form ,...,,,, xxx uuutxG is called a symmetry of the partial
differential equation
,,...,,, 2 mxxxt uuuuFu (1.6e)
if and only if equation (1.6e) remains unaffected under the substitution Guu
contained by the order . Hence,
GuFGuDt (1.6f)
must grasp up to order on any solution of (1.6g). Therefore, G must gratifies the
equation
,GuFGDt (1.6g)
where F is the Fréchet derivative of F.
Theorem 1.3 [87] Every Lie point, Lie-Bäcklund and non-local symmetry
x
uuxx
uuxXi
i
,...,,,...,, 11 (1.6h)
of differential equations
,,...,2,1,0,...,,, mu
FvvuuxF ss
(1.6i)
gives a conservation law for the system of differential equations containing Eqs. (1.6i)
and the adjoint equations
17
.,...,2,1,0,...,,,* mu
FvvuuxF ss
(1.6j)
Theorem 1.4 [28] For all n > 0, the KdV equation
0 xxxxn
t uuuuG (1.6k)
admits the multipliers
.1
1,,1 1
n
xx un
uu (1.6l)
The only supplementary acknowledged multipliers of the form
xxx uuutx ,,,,
are given by
,1if, nxut
.2if,3
1
3
1 3
nxuuut xx (1.6m)
Theorem 1.5 [28] For capricious wave speeds c(u), the only multipliers of form
xt uuutx ,,,,
divulge by the wave equation
0xxtt uucucuG (1.6n)
are given by
.,, xtxt xutuuu
Theorem 1.6 [28] For non-constant wave speed c(u), the wave equation (1.6n) admits
supplementary multipliers of form
xt uuutx ,,,, (1.6o)
iff 2
00
uucuc in terms of constants ., 00 uc
For these wave speeds the supplementary admitted multipliers are given by
18
.
,
,
0
02
02
uuxutu
uuxux
uutut
xt
x
t
(1.6p)
Theorem 1.7 [183] Consider a system of differential equations
0,...,,, 1 kuuux (1.6q)
captivating place from a variational theory, whose results are extrema of an exploit
integral J [x, u] with Lagrangian L[x, u]. If
uxauuuxaxx AAAiii ,,, (1.6r)
is a Lie point symmetry of J [x, u] and vuxWi ,, are defined by (1.6s).
.
,...
,1...
,
,1...
,,,
11
11
11
12
1
1
11
11
...
...
...
...
2
...
...
1
Ajji
Ajj
Ajji
jj
k
Aji
Aj
Ajji
jj
k
Ai
Ai
k
k
k
k
k
k
u
uxLv
u
uxLD
u
uxLv
u
uxLD
u
uxLvvuxW
(1.6s)
Then
1. the identity holds for capricious functions u(x);
uuxWuxLxuDuxLEu Aiiiu
AA ~,,,,~ (1.6t)
2. the limited conservation law
0~,, uuxWuLxuD Aiii (1.6u)
grasps for any result u(x) of Euler-Lagrange equations.
19
1.5 Analysis of the Methods
1.5.1. Further Improved )/( GG -Expansion Method
Consider the following nonlinear partial differential equation,
,0),,,,,,,,( zzyyttzyxt uuuuuuuuP (1.7)
where P is a polynomial in the unknown function ).,,,( tzyxuu The further improved
)/( GG -expansion method [23] proceeds in the following steps:
Step 1: The wave variable in four independent variables
)(),,,( utzyxu , ,tVzyx (1.8)
transforms (1.7) into an ordinary differential equation in the form
,0),,,,( uuuuH (1.9)
where primes stand for the ordinary derivatives with respect to .
Step 2: Integration of (1.9) yields constant(s) of integration, if possible. For simplicity,
the integration constant(s) may be neglected.
Step 3: Suppose that the solution of (1.9) can be expressed by means of a polynomial in
)/( GG as follows:
,)(0
in
ii
G
Gu
(1.10)
where i ( ,3,2,1i ) are constants provided 0n and )(= ξGG satisfies the
),()()()]([ 6422 GrGqGpG (1.11)
where qp, and r are arbitrary constants to be indomitable later.
20
Table 1.1. The solutions of (1.11) can be found in [259, 269]:
No )(ξG No )(ξG
1 2
1
22
2
))tanh(1(
)(sec
prpq
phqp or
2
1
22
2
))coth(1(
)(csc
prpq
phqp, 0p
6 2
12
)tan(2
)(sec
prpq
ppor
2
12
)cot(2
)(csc
prpq
pp, 0p , 0r
2 2
1
)2cosh(
2
qp
p
, 0p 0
7
2
1
22
2
644
rpqe
ep
p
p
, 0p
3 2
1
)2cos(
2
qp
p
or
2
1
)2sin(
2
qp
p
, 0p , 0 .
8 2
1
)2
1tanh(1
p
q
p or
2
1
)2
1coth(1
p
q
p0p , 0
4 2
1
)2sinh(
2
qp
p
, 0p , 0
9 2
1
4
2
641
p
p
erp
ep, 0p , 0q
5 2
1
2
)tanh(2
)(sec
prpq
php or
2
1
2
)coth(2
)(csc
prpq
php, 0p ,
0r
10
q
1 , 0p , 0r .
where rpq 42 .
21
Step 4: In (1.10), the confirmatory integer n can be found by applying the homogeneous
balancing principle between the leading order linear term(s) with the nonlinear term(s) of
the leading order in equation (1.9).
Step 5: Inserting (1.10) in (1.9) and utilizing (1.11) polynomials in )(ξGi and
)()( iGG are obtained. Equating to zero each coefficient of the polynomials capitulate
a system of equations for unidentified constants. The values of the unidentified constants
rqpαn ,,, and V can be found by solving the system of equations and putting the values
in equation (1.10), further novel and general exact solutions of equation (1.7) are
originated.
1.4.2 Extended Tanh Function Method
Consider the following nonlinear partial differential equation,
,0),,,,,,,,( zzyyttzyxt uuuuuuuuP (1.12)
where P is a polynomial in the unknown function ).,,,( tzyxuu
The extended tanh function method [60] works in the following steps:
Step 1: The wave variable,
)(),,,( utzyxu , ,tVzyx (1.13)
,0),,,,( uuuuH (1.14)
where primes stand for the ordinary derivative with respect to .
Step 2: If possible, integrate (1.14) term by term, one or more times. This yields
constant(s) of integration. For simplicity, the integration constant(s) can be set to zero.
Step 3: Suppose that the solution of (1.14) can be expressed by means of a polynomial in
)( as follows:
,)(0
n
iiu (1.15)
22
where i are constants and )( satisfy the following Riccati equation
)()( 2 A . (1.16)
The Riccati equation (1.16) has the subsequent solutions [60]:
(i) If 0A , then
)(tanh)( AA or ).(coth)( AA (1.17)
(ii) If 0A , then
)(tan)( AA or )(cot)( AA . (1.18)
(iii) If 0A , then
1
)( . (1.19)
Step 4: In (1.15), the affirmative integer n can be found by applying the homogeneous
balancing principle between the leading order linear term(s) with the nonlinear term(s) of
the leading order in equation (1.14).
Step 5: Inserting (1.15) in (1.14) and utilizing (1.16), polynomials in )( i are obtained. Equating to zero each coefficient of the polynomials capitulate a system of algebraic
equations for unidentified constants. The values of the unidentified constants rqpαn ,,,
and V can be found by solving the system of algebraic equations and putting the values
in equation (1.10), further novel and general exact solutions of equation (1.7) are
originated.
1.4.3. Improved )/( GG -Expansion Method
Consider the following nonlinear partial differential equation
,0),,,,,,( xxtxttxt uuuuuuF (1.20)
where F is a polynomial in unknown function txuu , and its partial derivatives.
The improved )/( GG -expansion method [126] progresses in the following steps:
23
Step 1: The wave variable
),(),( utxu ,tcx (1.21)
transforms (1.20) into an ordinary differential equation in the form
.0),,,,( uuuuP (1.22)
Step 2: Assume the solution of (1.22) can be expressed in )/( GG form as follows:
,)(
)()(
0
iM
ii
G
Gu
(1.23)
where i are constants given 0M and G is the solution of the nonlinear ordinary
differential equation
22 GCGBGGAGG , (1.24)
in which primes stand for the ordinary derivatives with respect to . A, B and C are
arbitrary constants which are to be indomitable at a later stage.
Using the general solutions of (1.24), following four solutions of )(/)( GG are:
Case 1. When 0B and ,0442 ACAB then
)(
)(
G
G= ,
)1(2)1(22
22
1
22
21
ecec
ecec
CC
B (1.25)
Case 2. When 0B and ,0442 ACAB then
)(
)(
G
G= ,
2cos
2sin
2sin
2cos
)1(2)1(221
21
cic
cic
CC
B (1.26)
Case 3. When 0B and ,0)1( CA then
)(
)(
G
G= ,
cossin
sincos
)1(21
21
cc
cc
C (1.27)
24
Case 4. When 0B
and ,0)1( CA then
)(
)(
G
G= ,
coshsinh
sinhcosh
)1(21
21
cic
cic
C (1.28)
where tcx , c is wave velocity; A, B, C and 21 , cc are real parameters.
Step 3: In (1.23), the positive integer M is obtained by applying the balancing principle
between the highest order linear term(s) with the nonlinear term(s) of the highest order in
(1.22).
Step 4: Inserting (1.23) into (1.22) and utilizing (1.24) polynomials in iGG )/( are
obtained. A system of algebraic equations for M and c is obtained by equating to zero
the coefficient of apiece resulted polynomial. After solving the obtained system of
algebraic equations the values of the unidentified constants M and c can be found and
substituting these values in (1.23), more general exact traveling wave solutions can be
established.
Xinhua and Zhen [230] consider the perturbed periodic “good” Boussinesq equation
,2xxxxxxxxtt uuuu (1.28a)
with initial and boundary conditions
,0,,0, xxuxxu t (1.28b)
...,,2,1,0,;,2;, jtxutxu jj (1.28c)
where ε is a petite positive integer, µ is a unvarying, φ and ψ are 2π-periodic
C functions gratifying
,02
0
2
0 dxxdxx (1.28d)
and ju represents the derivative with respect to x.
25
Theorem 1.8 [230] The solution of the initial and boundary value problem (1.28e)-
(1.28g)
,21 2xxxxxxxxtt uuuu (1.28e)
,;0,,;0, xxuxxu t (1.28f)
...,2,1,0,;,2;, jtxutxu jj (1.28g)
uniquely exists, such that
00;,;, Mtxutxu x (1.28h)
for all x, t ≥ 0 and 0 < |ε| ≤ 0 . 00 M is a positive constant.
1.4.4. Alternative )/( GG -Expansion Method
Consider the nonlinear PDE in the form
.0),,,,,,( txxxttxt uuuuuuF (1.29)
Step 1: The wave variable,
),(),( utxu ,tVx (1.30)
renovates (1.29) into an ODE in the form
,0),,,,( uuuuQ (1.31)
where primes stand for the ordinary derivative with respect to .
Step 2: Amalgamate (1.31) if possible, succumbs integration constant(s).
Step 3: The solution of (1.31) is articulated in the form of )/( GG as follows
,)(0
in
ii
G
Gau
,0na (1.32)
and G satisfies
,2GqGprG (1.33)
26
where ia , qp, and r are arbitrary constants to be resolute later on.
Accordingly, different families of exact solutions of (1.33) are follows from [278]:
Family 1:
When 042 qrp and ),0or (0 qrqp the solutions of (1.33) are:
22
1 42
1tan4
2
1pqrpqrp
qG ,
,42
1cot4
2
1 222
pqrpqrp
qG
,4sec4tan42
1 2223 pqrpqrpqrp
qG
,4csc4cot42
1 2224 pqrpqrpqrp
qG
,44
1cot4
4
1tan42
4
1 2225
pqrpqrpqrp
qG
,
4sin
4cos4)4()(
2
12
22222
6
BpqrA
pqrpqrApqrBAp
qG
,
4sin
4cos4)4()(
2
12
22222
7
BpqrA
pqrpqrApqrBAp
qG
wherever A and B are non-zero real constants and gratifying the form 022 BA .
,
42
1cos4
2
1sin4
42
1cos2
222
2
8
pqrppqrpqr
pqrr
G
,
42
1cos)4(4
2
1sin
42
1sin2
222
2
9
pqrpqrpqrp
pqrr
G
27
,
)4(4cos4sin)4(
4cos2
2222
2
10
pqrpqrppqrpqr
pqrrG
,
)4(4cos)4(4sin
4sin2
2222
2
11
pqrpqrpqrpqrp
pqrrG
.
)4(44
1cos)4(24
4
1cos4
4
1sin2
44
1cos4
4
1sin4
222222
22
12
pqrpqrpqrpqrpqrp
pqrpqrr
G
Family 2:
When 042 qrp and ),0or (0 qrqp the solutions of (1.29) are:
qrpqrpp
qG 4
2
1tanh4
2
1 2213 ,
,42
1coth4
2
1 2214
qrpqrpp
qG
,4sec4tanh42
1 22215 qrphiqrpqrpp
qG
,4csc4coth42
1 22216 qrphqrpqrpp
qG
,44
1coth4
4
1tanh42
4
1 22217
qrpqrpqrpp
qG
,
4sinh
4cosh4)4()(
2
12
22222
18
BqrpA
qrpqrpAqrpBAp
qG
28
,
4sinh
4cosh4)4()(
2
12
22222
19
BqrpA
qrpqrpAqrpABp
qG
somewhere A and B are non-zero real constants and gratify the stipulation 022 AB .
,
42
1cosh4
2
1sinh4
42
1cosh2
222
2
20
qrppqrpqrp
qrpr
G
,
42
1sinh4
2
1cosh4
42
1sinh2
222
2
21
qrppqrprqrp
qrpr
G
,
44cosh4sinh4
4cosh2
2222
2
22
qrpiqrppqrpqrp
qrprG
,
44cosh44sinh
4sinh2
2222
2
23
qrpqrpqrpqrpp
qrprG
.
444
1cosh424
4
1cosh4
4
1sinh2
44
1cosh4
4
1sinh4
222222
22
24
qrpqrpqrpqrpqrpp
qrpqrpr
G
Family 3:
When 0r and ,0qp the solutions of (1.29) are:
,
sinhcosh25
ppdq
dpG
,sinhcosh
sinhcosh26
ppdq
pppG
where d is an arbitrary constant.
29
Family 4:
When 0q and ,0 pr the solution of (1.29) is:
,1
1
27dq
G
where 1d is an arbitrary constant.
Step 4: The positive integer n in equation (1.32) is obtained by the homogeneous
balancing principle among the leading order linear term(s) with the nonlinear term(s) of
the leading order in equation (1.31).
Step 5: Inserting (1.32) in (1.31) and utilizing (1.33) polynomials in iG and iG are
obtained. Equating to zero every coefficient of the polynomials, succumbs a system of
algebraic equations for different unidentified constants. After solving the system, the
value of the unidentified constants can be found and putting the values in (1.32) precise
and different types of the traveling wave results of (1.29) are obtained.
1.4.5. )/1,/( GGG -Expansion Method
Suppose a nonlinear partial differential equation for ),,( tzxP is given by
,0),,,,,,( zxxxzxt uuuuuuP (1.34)
The )/1,/( GGG -expansion method [116] proceeds as follows:
Step 1: The wave variable
),(PP ,tVzx (1.35)
where is nonzero constant, )(P the function of , converts (1.34) into an ordinary
differential equation as:
.0),,,,( uuuVuQ (1.36)
Step 2: Integrating (1.36) one or more times, yields constant(s) of integration. For
simplicity, the integration constant(s) may be set to zero.
Step 3: According to the projected method, the solution of (1.36) can be expressed as
30
,)( 1
10
nM
nn
nM
nnu (1.37)
where n and n are constants to be find out later on and )( and )( are given by
G
G)( ,
,
1)(
G (1.38)
which satisfy
.)()( GG (1.39)
The equations (1.38) and (1.39) yield
,2 . (1.40)
The three cases of the general solution of (1.39) are:
Case 1: When ,0 the general solution of (1.39) is
,coshsinh
BAG
and we have
,22
22
2
(1.41)
where .22 BA
Case 2: When ,0 the general solution of (1.39) is
,cossin
BAG
and we have
,22
22
2
(1.42)
where .22 BA
Case 3: When 0 the general solution of (1.39) is
31
and hence
,22
1 2
2
2
BA
(1.43)
where A and B are arbitrary constants.
Step 4: In (1.37), the positive integer M is consummate by balancing principle among
the linear term of utmost order with the utmost order nonlinear term.
Step 5: Inserting (1.37) in (1.36) along with (1.40) and (1.41) will yield a polynomial in
and , in which the degree of is not bigger than 1. Equating like powers of M
and M equal to zero, yields a set of algebraic equations for n Mn ,,3,2,1,0 and
n BAMn ,,0,,,,3,2,1 and .V
Step 6: Solve the obtained system in step 5 for n ,,,3,2,1,0 Mn n
BAMn ,,,,,,3,2,1 andV to determine the values of these constants. Putting the
values of these constants in (1.37), the hyperbolic type of solutions of (1.34) are obtained.
Step 7: Similarly, inserting (1.37) in (1.36) along with (1.40) and (1.42) for 0 (or
(1.40) and (1.43) for 0 ), the traveling wave solutions of (1.34) expressed by
trigonometric (or by rational) functions respectively are obtained.
Theorem 1.9 [128] If the functions gg and hh satisfy the equation
nkhhhg
u
uugfhd
dgv
k
k
n
1,......~
,~.,.,.~, 1
(1.43a)
where v is some constant, then
hvtxgtxu ,, (1.43b)
provides a traveling wave solution to the following equation
.1,,,...,,,,
k
x
uuuuutxfu
k
kkn
xt (1.43c)
32
1.4.6. Novel )/( GG -Expansion Method
Consider the nonlinear partial differential equation of the type
.0),,,,,,,,,( ttzzyyxxzyxt uuuuuuuuuq (1.44)
The steps of the novel GG / -expansion method [26] are as follows:
Step 1: The wave variable
),(),,,( utzyxu ,tVzyx (1.45)
transforms (1.44) into an ordinary differential equation
,0),,,,( uuuuP (1.46)
which contains various ordinary derivatives of the unknown function u with respect to .
Step 2: Assume the solution of (1.46) is of the form
,)()(
m
mi
i
i ku (1.47)
where )(
)()(
G
G . (1.48)
Here m or m may be zero, but at the same time both can not be zero. i and k are
calculated later and G satisfy
.)( 22 GCGBGGAGG (1.49)
The Cole-Hopf renovation )(
)()(ln)(
G
GG
reduces (1.49) to the Riccati
equation:
.)()1()()( 2 CAB (1.50)
Equation (1.50) has individual twenty five solutions (see Zhu, [278] for details).
Step 3: The affirmative integer m in equation (1.47) is obtained by applying the
balancing principle between the linear term(s) and the nonlinear term(s) of the leading
order in equation (1.46).
Step 4: Polynomials in iGGk / and iGGk
/ are obtained by inserting (1.47)
together (1.48) and (1.49) in (1.48). A system of algebraic equations for i
33
),,,2,1,0( mi k and V is obtained by collecting each coefficient of the resulted
polynomials to zero.
Step 5: The value of the constants can be found by solving the obtained system. By
inserting the values of the constants together with the solutions of (1.49), various types of
the solutions of the nonlinear evolution equation (1.44) can be found.
Lemma 1.1 [106] Let VUT : be a bounded linear operator and let pu be a
convergent sequence in U with u as its limit, then pu converges to u in U implies that
puA converges to uA in V.
1.4.7. The Fractional Novel )/( GG -Expansion Method
Assume a fractional partial differential equation is given by
,10,0,...,,,, uDuDuuuS txtx (1.51)
where uDx and uDt
are modified Riemann-Liouville derivatives of txu , .
The fractional novel )/( GG -expansion method [202] works as follows:
Step 1: A fractional complex renovation was projected by Li et al. [115] which transform
the given fractional PDE into an ODE. The traveling wave variable
,, utxu
,11
0
t
Vx
L (1.52)
reduces (1.51) into an ordinary differential equation of integer order
,0,...,,, uuuuP (1.53)
where 0 and, VL are arbitrary constants with .0, VL
Step 2. Integrating (1.53) if possible, gives up constant(s) of integration which can be
premeditated later.
Step 3: Assume the trial solution of (1.53) is
,)()(
m
mi
i
i ku (1.54)
where
.)(
)()(
G
G (1.55)
34
Herein m or m may be zero, but at the same time both can not be zero. i and k are
calculated later and G gratifies
,)( 22 GCGBGGAGG (1.56)
where primes stand for the ordinary derivative with respect ; A , B and C are factual
constants.
The Cole-Hopf transformation )(/)()(ln)( GGG diminishes (1.56) in
the following Riccati equation:
.)()1()()( 2 CAB (1.57)
The solutions of the equation (1.57) can be found in [278].
Step 4: The confirmatory integer m can be found by applying the homogeneous
balancing principle between linear term(s) and the nonlinear term(s) of the leading order
in equation (1.53).
Step 5: Polynomials in iGGk / and iGGk
/ are obtained by inserting (1.54)
together (1.55) and (1.56) in (1.53). A system of algebraic equations for i
),,,2,1,0( mi k, L and V is obtained by collecting each coefficient of the resulted
polynomials to zero.
Step 6: The value of the constants can be found by solving the obtained system. By
inserting the values of the constants together with the solutions of (1.56), various types of
the solutions of (1.51) can be found.
Consider the Camassa-Holm equation
Rxtuuuuuuuuuu xxxxxxxxtxxxxtxxt ,0,2 (1.57a)
with initial condition
,1,0, 0 sRHxuxu s
where RHH ss denotes the Sobolev space and ,, are constant and .4/1,0
35
Theorem 1.10 [114] Assume sHu 0 for some constant .2
3s Then the problem
,,,
,,022
1
0
2212
Rxxutxu
Rxtu
uuIuuu xxxxt
(1.57b)
has a unique solution txu , in sHTC ;,0 for T > 0.
36
Chapter 2
Exact Solutions of Nonlinear Evolution Equations by
Further Improved )/( GG -Expansion and Extended Tanh-
Function Methods
37
2.1. Introduction
The rapid development of nonlinear sciences has provided an ample opportunity to
benefit from a wide range of reliable and efficient techniques which are of significant in
tackling physical problems even of highly multifarious nature. After the surveillance of
solitary phenomena by John Scott Russell [191] in 1834 and since the Korteweg-de Vries
(KdV) equation was solved by Gardner et al. [64] by the inverse scattering method,
finding exact solutions of nonlinear evolution equations (NLEEs) has turned out to be
one of the most thrilling and predominantly dynamic areas of research. The manifestation
of solitary wave solutions in nature is quite prevalent like Bell-shaped 2sec h solutions
and kink-shaped tanh solutions, model wave phenomena in elastic media, plasmas, solid
state physics, fluids etc. There are various schemes to unearth the exact solutions of
nonlinear partial differential equations. Apart from their physical importance, the closed-
form solutions of NLEEs, if accessible assist the numerical solvers in comparison, and
prove obliging in the immovability analysis. Soliton theory carries many methods to deal
with the problem of solitary wave solutions for NLEEs such as: Truncated Painleve
Expansion [112], Weierstrass Elliptic Function [111], Inverse Scattering [18], Jacobi
Elliptic Function Expansion [127], Generalized Riccati Equation [176], Tanh-Coth [227],
Wronskian and Casorati [124, 142, 146] methods.
Later on, Wang et al. [217] presented a reliable technique, which is called )/( GG -
expansion method and obtained exact traveling wave solutions for the nonlinear
evolution equations (NLEEs). In this method, following differential equation with
constant coefficients is used as supplementary equation
.0)()()( GGG
In this chapter, further improved )/( GG -expansion method and extended tanh-function
method are used for finding traveling wave solutions of nonlinear evolution equations
[123,195, 196, 220, 239]. In first method following differential equation is used as an
auxiliary equation
).()()()]([ 6422 GrGqGpG
38
This modified version gives more general and new solutions as compared to traditional
)/( GG -expansion method. This modified version is discussed by Akbar et al. [23] and
Zayed [266] to find the soliton solutions of nonlinear evolution equations. In extended
tanh-function method, we shall utilize the concept of traditional )/( GG -expansion
method coupled with following nonlinear Riccati equation as an auxiliary equation.
.)()( 2 A
This method has less computational work as compared to conventional )/( GG -
expansion method and further improved )/( GG -expansion method. In some cases,
solutions are identical with )/( GG -expansion method, extended tanh-function method
and further improved )/( GG -expansion method by selecting the suitable values of the
arbitrary constants. Fan [58], El-Wakil et al. [56, 57], Fan and Hon [59] and Abdou [17]
have successively applied extended tanh-function method to seek the traveling solutions
of nonlinear partial differential equations. It is important to observe that the proposed
algorithms give different solutions. These algorithms are more reliable and efficient as
compared to the fundamental )/( GG -expansion scheme.
2.2. Numerical Examples
In this section, to verify the efficiency of well known direct computational methods: further improved )/( GG -expansion method and extended tanh-function methods, few
intricate examples are given. The solutions obtained by the two techniques are useful,
efficient, and trustworthy. The presented techniques provide additional new and exact
traveling wave solutions than the other methods.
Example 2.2.1. The (3 + 1)-dimensional Potential-YTSF Equation
Consider the (3 + 1)-dimensional potential-YTSF equation [196] in the form
.03244 yyzxxzxxzxxxtx uuuuuuu (2.1)
The use of the wave variable
),(),,,( utzyxu ,tVzyx (2.2)
39
into the partial differential equation (2.1) readily gives ODE and upon integrating once
with integration constants are considered zero yields
0)(3)34( 2 uuuV , (2.3)
Taking into consideration the homogeneous balance between u and 2)(u in (2.3), we
deduce that 1n . Consequently, the solution of equation (2.3) becomes
,0,)( 101 GGu (2.4)
where 0 and 1 are constants to be indomitable later and )(G gratifies the following
nonlinear auxiliary equation,
).()()()]([ 6422 GrGqGpG (2.5)
Inserting (2.4) and (2.5) in (2.3), a system of algebraic equations in different powers of
G is obtained as follows:
,0443: 1112 pqVqqG
,0686323: 21111
221
4 qrVrprqG (2.6)
,04812: 121
6 qrqrG
.04812: 21
221
8 rrG
Solving the above system (2.6) and the following two sets of solution are obtained as:
Set 1.
,41 ,00 ,2 rpq ,4
3 pV (2.7)
Set 2.
,41 ,00 ,0q ,4
34 pV (2.8)
where ,0 p and r are arbitrary constants.
Therefore the trial solution for the set 1 becomes:
,4)( 0
G
Gu (2.9)
where tpzyx )4
3( .
40
The succeeding families of exact solutions due to step 3 of section 1.5.1 are:
Family 1. If ,0p the form of the solution is
2
1
22
2
))coth(1(
)(csc)(
prpq
phqpG or .
))coth(1(
)(csc)(
2
1
22
2
prpq
phqpG
In these cases the ratio is
rpqpprpprppq
rpprppprpppqp
G
G
2222
22
)cosh()sinh(2)(cosh2)(cosh
)(cosh2)cosh()sinh(2)cosh()sinh(
or
.
)cosh()sinh(2)(cosh2)(cosh
)(cosh2)cosh()sinh(2)cosh()sinh(2222
22
rpqpprpprppq
rpprppprpppqp
G
G
Because ,2 rpq consequently the solution is
02
2
2)2tanh(2)2(sec3
)2(sec84)(
pph
phppu
or .2)2tanh(2)2(sec3
)2(sec84)( 02
2
pph
phppu (2.10)
Family 2. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or .
)coth(2
)(csc)(
2
1
2
prpq
phpG
Then the ratio is
)sinh(2)cosh()cosh(
)(cosh2)cosh()(sinh 2
prppqp
rpprpppqp
G
G
or
.)cosh(2)sinh()sinh(
)(cosh2)cosh()(sinh 2
prppqp
rpprpppqp
G
G
Because ,2 rpq consequently the solution is
0)(tanh22)( pppu or .)(coth22)( 0 pppu (2.11)
41
Family 3. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or .
)cot(2
)(csc)(
2
1
2
prpq
ppG
Then the ratio is
)(cos(sin2)(cos
)(cos)sin()(cos2 2
pqprpp
ppqprprpp
G
G
or
.)(sin(cos2)(sin
)(cos)sin()(cos2 2
pqprpp
ppqprprpp
G
G
Because ,2 rpq consequently the solution is
0)2sec()2(tan1
1)2(tan4)(
pp
ppu
or
.)2sec()2(tan1
1)2(tan4)( 0
pp
ppu
(2.12)
Family 4. If ,0p ,0 the type of the solution is
2
1
)2
1tanh(1)(
pq
pG or .)
2
1coth(1)(
2
1
pq
pG
In these cases the ratio is
)
2
1tanh(1
4p
p
G
G or .)
2
1coth(1
4
p
p
G
G
Subsequently the traveling wave solution is
0)2
1tanh(1)(
ppu or .)
2
1coth(1)( 0
ppu (2.13)
Family 5. If ,0p the type of the solution is
2
1
22
2
644)(
rpqe
epG
p
p
.
42
The ratio is
.
64168
6416224
24
rpqeqe
rpqep
G
Gpp
p
Because ,2 rpq consequently the solution is
,16
4)( 02
2
p
p
erp
epu
(2.14)
where tpzyx )4
3( .
While, the trial solution for the set 2 becomes:
,4)( 0
G
Gu (2.15)
where tpzyx )4
34( .
The succeeding families of exact solutions due to step 3 of section 1.5.1 are:
Family 6. If ,0p ,0 the kind of the solution is
.)2cosh(
2)(
2
1
qp
pG
Because ,0q then .0r Then the ratio for the case is
).2tanh( ppG
G
Hence, the traveling wave solution is
.)2tanh(4)( 0 ppu (2.16)
Family 7. If ,0p ,0 the form of the solution is
.)2sinh(
2)(
2
1
qp
pG
43
Because ,0q then .0r The ratio for the case is
).2coth( ppG
G
Hence, the obtained solution in this case is
.)2coth(4)( 0 ppu (2.17)
Family 8. If ,0p ,0 the form of the solution is
2
1
)2cos(
2)(
qp
pG
or .
)2sin(
2)(
2
1
qp
pG
Because ,0q then .0r Thus the ratio is
)2tan( ppG
G
or ).2cot( pp
G
G
Consequently, the traveling wave solution is
0)2tan(4)( ppu or .)2cot(4)( 0 ppu (2.18)
Family 9. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or .
)coth(2
)(csc)(
2
1
2
prpq
phpG
Because ,0q the ratio in this case is
.)coth()tanh(2
1 ppp
G
G
Consequently, the solution is
.)coth()tanh(2)( 0 pppu (2.19)
Family 10. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or .
)cot(2
)(csc)(
2
1
2
prpq
ppG
44
Because in this case ,0q therefore the ratio is
.)tan()cot(2
1 ppp
G
G
.)tan()cot(2)( 0 pppu (2.20)
Family 11. If ,0p ,0q the form of the solution is
.641
)(2
1
4
2
p
p
erp
epG
Then the ratio is
,4
coth8
1
rrG
G
where 164 rp .
Hence, for the family 11 the solution is
.4
coth2
1)( 0
rru (2.21)
Family 12. If ,0p ,0r the form of the solution is
.1
)(
q
G
Then the ratio is
.1
G
G
Consequently, the solution is
,4
)( 0
u (2.22)
where tpzyx )4
34( .
45
Now, solving (2.1) by using extended tanh-function method. The solution of (2.1) is
,)()( 01 u (2.23)
.)()( 2 A (2.24)
Inserting (2.23) and (2.24) in (2.3), following polynomial equation in is obtained as
follows:
.0)3234(
)()3684()()63(
221
2111
21
2111
41
21
AAAVA
AAV
(2.25)
Equating to zero each coefficient of the polynomial equation (2.25), a system of
equations is obtained and after solving the system, following solution is obtained:
,21 ,00 ,4
3AV (2.26)
where 0 and A are arbitrary constants. Then according to step 3 of section 1.5.2, the
exact solutions of (2.1) are:
When 0A , the form of the solution is
0)tanh(2)( AAu or .)coth(2)( 0 AAu (2.27)
When ,0A the form of the solution is
0)tan(2)( AAu or .)cot(2)( 0 AAu (2.28)
When ,0A the form of the solution is
,2
)( 0
u (2.29)
where
.)4
3( tAzyx
46
Remark 2.1: The results given in (2.27) and (2.16), (2.17) are alike, if we put ,4 pA
where .0p
Remark 2.2: The results given in (2.28) and (2.18) are alike, if we put ,4 pA
where .0p
Remark 2.3: Result in (2.29) is alike to (2.22).
Example 2.2.2. The (3 + 1)-Dimensional Jimbo-Miwa Equation
Consider the (3 + 1)-dimensional Jimbo-Miwa equation [123] in the form
.03233 zxtyyxxxxyyxxx uuuuuuu (2.30)
The Jimbo-Miwa equation is model equation for water waves of long wavelength with
weakly non-linear refurbishing forces and frequency dispersion [92]. The equation can
also be used to model waves in ferromagnetic media, as well as two-dimensional matter-
wave pulses in Bose-Einstein condensates.
Now solving (2.30) by further improved )/( GG -expansion method. Using (2.2) in
(2.30) that converts the given partial differential equation in an ordinary differential
equation and on integration with zero constant of integration yields:
.0)(3)32( 2 uuuV (2.31)
Taking into consideration the balancing principle between the u and 2)(u come out in
(2.33), we deduce that .1n Therefore, the trial solution can be written as
.)( 01
G
Gu (2.32)
Inserting (2.32) and (2.5) in (2.31), following algebraic equations in G are obtained as
follows:
,0432: 1112 pqqqVG
,0646323: 21111
221
4 qrVrprqG
,04812: 121
6 qrqrG (2.33)
.04812: 21
221
8 rrG
47
Solving the algebraic equations (2.33), the solutions are:
Set 1.
,2
32,2,,4 001 pVrpq (2.34)
Set 2.
,2
38,0,,4 001 pVq (2.35)
where 0 , p and r are arbitrary constants.
The form of the trial solution for the set 1 becomes
,4)( 0
G
Gu (2.36)
where tpzyx )2
32( .
The succeeding families of exact solutions due to step 3 of section 1.5.1 are:
Family 1. If ,0p the form of the solution is
2
1
22
2
))tanh(1(
)(sec)(
prpq
phqpG or .
))coth(1(
)(csc)(
2
1
22
2
prpq
phqpG
In these cases, the ratio is
rppprpprppq
rpprppprpppqp
G
G
)cosh()sinh(2)(cosh2)(cosh
))(cosh2)cosh()sinh(2)cosh()sinh((222
22
or
.)cosh()sinh(2)(cosh2)(cosh
))(cosh2)cosh()sinh(2)cosh()(sinh(2222
22
rpqpprpprppq
rpprppprpppqp
G
G
Because ,2 rpq subsequently, the traveling wave solution is
48
02
2
2)2tanh(2)2(sec
)2(sec84)(
pph
phppu
or .2)2tanh(2)2(sec3
)2(sec84)( 02
2
pph
phppu (2.37)
Fig. 2.1. Shows the form of the kink-type solution of (2.37) for .0,0,2,1 0 zyp
Family 2. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or .
)coth(2
)(csc)(
2
1
2
prpq
phpG
Then the ratio is
))sinh(2)cosh(()cosh(
))(cosh2)cosh()(sinh( 2
prppqp
rpprpppqp
G
G
or .))cosh(2)sinh(()sinh(
))(cosh2)cosh()(sinh( 2
prppqp
rpprpppqp
G
G
Because ,2 rpq subsequently, following traveling wave solution is
0)(tanh22)( pppu or .)(coth22)( 0 pppu (2.38)
49
Fig. 2.2. Shows the exact kink-type solution of (2.38) for .0,0,2,1 0 zyp
Family 3. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or .
)cot(2
)(csc)(
2
1
2
prpq
ppG
Then the ratio is
))(cos(sin2()(cos
))(cos)sin()(cos2( 2
pqprpp
ppqprprpp
G
G
or .))(sin(cos2()(sin
))(cos)sin()(cos2( 2
pqprpp
ppqprprpp
G
G
Because ,2 rpq consequently, obtained solution is
0)2sec()2(tan1
)1)2((tan4)(
pp
ppu
or .)2sec()2(tan1
)1)2((tan4)( 0
pp
ppu
(2.39)
50
Fig.2.3. Solution (2.39) represents the exact periodic traveling wave solution for ,0,1 0 p .0,0 zy
Family 4. If ,0p ,0 the form of the solution is
2
1
)2
1tanh(1)(
p
q
pG or .)
2
1coth(1)(
2
1
p
q
pG
Then the ratio is
)
2
1tanh(1
4p
p
G
G or .)
2
1coth(1
4
p
p
G
G
Subsequently, the solution is obtained as
0)2
1tanh(1)(
ppu or .)
2
1coth(1)( 0
ppu (2.40)
Family 5. If ,0p the form of the solution is
.64)4(
)(2
1
22
2
rpqe
epG
p
p
The ratio in this case is
.64168
)6416(224
24
rpqeqe
rpqep
G
Gpp
p
51
Because ,2 rpq consequently, the solution is
,16
4)( 02
2
p
p
erp
epu
(2.41)
where tpzyx )2
32( .
The form of the trial solution for the set 2 becomes:
,4)( 0
G
Gu (2.42)
where tpzyx )2
38( .
The successive families of exact solutions due to step 3 of section 1.5.1 are:
Family 6. If ,0p ,0 the form of the solution is
.)2cosh(
2)(
2
1
qp
pG
Because ,0q then .0r The ratio in this case is
).2tanh( ppG
G
Consequently, the wave solution is obtained in the form
.)2tanh(4)( 0 ppu (2.43)
52
Fig. 2.4. Shows the form of the exact kink solution of (2.43) for .0,0,1,4/1 0 zyp
Family 7. If ,0p ,0 the form of the solution is
.)2sinh(
2)(
2
1
qp
pG
Because ,0q then .0r The ratio in this case is
)2coth( ppG
G
.
Consequently, the obtained solution is
.)2coth(4)( 0 ppu (2.44)
Family 8. If ,0p ,0 the solution of (2.5) has the form
2
1
)2cos(
2)(
qp
pG
or .
)2sin(
2)(
2
1
qp
pG
Since ,0q then .0r Thus the ratio is
)2tan( ppG
G
or ).2cot( pp
G
G
Consequently, the traveling wave solution is
53
0)2tan(4)( ppu or .)2cot(4)( 0 ppu (2.45)
Family 9. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
Because in this case ,0q the ratio is
)coth()tanh(2
1 ppp
G
G
.
Consequently, the solution is
.)coth()tanh(2)( 0 pppu (2.46)
Family 10. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
Because in this case ,0q the ratio is
)tan()cot(2
1 ppp
G
G
.
Consequently, the traveling wave solution is
.)tan()cot(2)( 0 pppu (2.47)
Fig. 2.5. Solution (2.47) explains the single soliton for ,3,2 0 p .0,0 zy
54
Family 11. If ,0p ,0q the form of the solution is
2
1
4
2
641)(
p
p
erp
epG .
In this case the ratio is
rrG
G
4coth
8
1 ,
where 164 rp .
Consequently, the solution is obtained in the form
.4
coth2
1)( 0
rru (2.48)
Family 12. If ,0p ,0r then the form of the solution is
q
G1
)( .
In this case the ratio is
1
G
G.
Consequently, the traveling wave solution is obtained in the form
,4
)( 0
u (2.49)
where tpzyx )2
38( .
Now solving (2.30) by using the extended tanh-function method. The solution of (2.30)
can be represented as
,)()( 01 u (2.50)
where )( satisfy the Riccati equation,
55
).()( 2 A (2.51)
Substituting (2.50) and (2.51) in (2.31), following polynomial equation in is obtained
as follows:
0)3232(
)()3682()()63(
221
2111
21
2111
41
21
AAAVA
AAV
(2.52)
Equating to zero each coefficient of (2.52), a system of equations is obtained and solving
the system, following solution is attained:
,22
3,,2 001
AV (2.53)
where 0 and A are arbitrary constants. Then according to step 3 of section 1.5.2, the
exact solutions of (2.30) are:
When ,0A the form of the solution is
0)tanh(2)( AAu or ,)coth(2)( 0 AAu (2.54)
When 0A , the form of the solution is
0)tan(2)( AAu or ,)cot(2)( 0 AAu (2.55)
When 0A , the form of the solution is
,2
)( 0
u (2.56)
where .22
3tAzyx
Example 2.2.3. The (2 + 1)-Dimensional CBS Equation
Consider the CBS equation [220] in the form
.024 zxxzxxzxxxtx uuuuuu (2.57)
The interface of a Riemann wave proliferating along the z-axis with a long wave along
the x-axis is described by Calogero-Bogoyavlenskii-Schiff equation. The (2 + 1)-
56
dimensional CBS equation occur in a non restricted form, but it can be written as a
system of differential equations and, in potential form, as a fourth-order partial
differential equation and admits a Lax representation and is integrable by the one-
dimensional inverse scattering transform. Bruzon et al. [41] find the symmetry reductions
and exact solutions of (2 + 1)-dimensional integrable CBS equation by using the classical
and nonclassical methods.
Now solving (2.57) by further improved )/( GG -expansion method. Using the traveling
Using the wave variable (1.8) that converts (2.57) into an ordinary differential equation
and upon integrating once with integration constant zero yields:
.0)(3 2 uuuV (2.58)
Applying the balancing principle between u and 2)(u in (2.58), we deduced that .1n
Thus,
.)( 10
G
Gu (2.59)
Substituting (2.59) and (2.5) in (2.58), following system of algebraic equation in G is
acquired:
,04: 112 pqqVG
,062323: 2111
221
4 qrVprqG
,04812: 12
16 qrqrG (2.60)
.04812: 21
221
8 rrG
Solving the above system of equations, two solution sets are obtained as follows:
Set 1.
,4,2,4, 100 pVrpq (2.61)
where 0 , p and r are arbitrary constants.
Set 2
,16,0,4, 100 pVq (2.62)
where 0 and p are arbitrary constants.
The form of the trial solution for the set 1 becomes:
57
G
Gu 4)( 0 , (2.63)
where .4 tpzx
The ensuing families of exact solutions due to step 3 of section 1.5.1 are:
Family 1. If ,0p the form of the solution is
2
1
22
2
))tanh(1(
)(sec)(
prpq
phqpG or
2
1
22
2
))coth(1(
)(csc)(
prpq
phqpG .
In these cases the ratio is
rppprpprppq
rpprppprpppqp
G
G
)cosh()sinh(2)(cosh2)(cosh
))(cosh2)cosh()sinh(2)cosh()sinh((222
22
or rpqpprpprppq
rpprppprpppqp
G
G
2222
22
)cosh()sinh(2)(cosh2)(cosh
))(cosh2)cosh()sinh(2)cosh()(sinh(
.
Because ,2 rpq consequently, the solution is
2)2tanh(2)2(sec
)2(sec84)(
2
2
0
pph
phppu
or 2)2tanh(2)2(sec3
)2(sec84)(
2
2
0
pph
phppu
. (2.64)
Family 2. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
Then, the ratio is
))sinh(2)cosh(()cosh(
))(cosh2)cosh()(sinh( 2
prppqp
rpprpppqp
G
G
or ))cosh(2)sinh(()sinh(
))(cosh2)cosh()(sinh( 2
prppqp
rpprpppqp
G
G
.
Because ,2 rpq consequently, the wave solution is
58
)(tanh22)( 0 pppu or .)(coth22)( 0 pppu (2.65)
Family 3. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
Then, the ratio is
))(cos(sin2()(cos
))(cos)sin()(cos2( 2
pqprpp
ppqprprpp
G
G
or ))(sin(cos2()(sin
))(cos)sin()(cos2( 2
pqprpp
ppqprprpp
G
G
.
Because ,2 rpq consequently, the wave solution is
)2sec()2(tan1
)1)2((tan4)( 0
pp
ppu
or .)2sec()2(tan1
)1)2((tan4)( 0
pp
ppu
(2.66)
Family 4. If ,0p ,0 the form of the solution is
2
1
)2
1tanh(1)(
pq
pG or
2
1
)2
1coth(1)(
pq
pG .
Then, the ratio is
)2
1tanh(1
4p
p
G
G or
)2
1coth(1
4p
p
G
G.
Subsequently, the traveling wave solution is
)2
1tanh(1)( 0 ppu or .)
2
1coth(1)( 0
ppu (2.67)
59
Family 5. If ,0p the form of the solution is
2
1
22
2
64)4()(
rpqe
epG
p
p
. .
The ratio in this case is
rpqeqe
rpqep
G
Gpp
p
64168
)6416(224
24
.
Because ,2 rpq consequently, the attained wave solution is
,16
4)(
2
2
0
p
p
erp
epu
(2.68)
where tpzx 4 .
For the set 2, the solution is:
,4)( 0
G
Gu (2.69)
where tpzx 16 .
The ensuing families of exact solutions due to step 3 of section 1.5.1 are:
Family 6. If ,0p ,0 the form of the solution is
2
1
)2cosh(
2)(
qp
pG
.
Because ,0q then ,0r so the ratio in this case becomes
)2tanh( ppG
G
.
Consequently, the obtained traveling wave solution is
).2tanh(4)( 0 ppu (2.70)
60
Family 7. If ,0p ,0 the solution of (2.5) has the form
2
1
)2sinh(
2)(
qp
pG
.
Because ,0q then .0r In this case the ratio is
)2coth( ppG
G
.
Consequently, the traveling wave solution is
).2coth(4)( 0 ppu (2.71)
Family 8. If ,0p ,0 the solutions of (2.5) has the form
2
1
)2cos(
2)(
qp
pG
or
2
1
)2sin(
2)(
qp
pG
.
Since ,0q then .0r Thus the ratio is
)2tan( ppG
G
or )2cot( pp
G
G
.
Consequently, the traveling wave solution is
)2tan(4)( 0 ppu or ).2cot(4)( 0 ppu (2.72)
Family 9. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
Because ,0q the ratio in this case is
)coth()tanh(2
1 ppp
G
G
.
.
61
Consequently, the traveling wave solution is
.)coth()tanh(2)( 0 pppu (2.73)
Family 10. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
Because ,0q so in this case the ratio is
)tan()cot(2
1 ppp
G
G
.
Consequently, the traveling wave solution is
.)tan()cot(2)( 0 pppu (2.74)
Family 11. If ,0p ,0q the form of the solution is
2
1
4
2
641)(
p
p
erp
epG .
For this case the ratio is
rrG
G
4coth
8
1 ,
where 164 rp .
Consequently, the solution is
.4
coth2
1)( 0
rru
(2.75)
Family 12. If ,0p ,0r then the form of the solution is
qG
1)( .
62
For this case the ratio becomes
1
G
G.
Consequently, the solution is
,4
)( 0
u (2.76)
where .16 tpzx
Now solving (2.57) by using extended tanh-function method. The solution of (2.57) can
be represented as
),()( 10 u (2.77)
where )( satisfy the Riccati equation,
).()( 2 A (2.78)
Substituting (2.77) and (2.78) in (2.58), following polynomial equation in is we
obtained as follows:
.0)32(
)()68()()63(22
12
11
22111
41
21
AAVA
AAV
(2.79)
A system of algebraic equations is obtained by equating to zero each coefficient of (2.79)
and after, the obtained solution is
,4,2, 100 AV (2.80)
where 0 and A are arbitrary constants. Then according to step 3 of section 1.5.2, the
exact solutions of (2.57) are
When 0A , the form of the solution is
)tanh(2)( 0 AAu or ).coth(2)( 0 AAu (2.81)
When ,0A the form of the solution is
)tan(2)( 0 AAu or ).cot(2)( 0 AAu (2.82)
When 0A , the form of the solution is
63
,2
)( 0
u (2.83)
where .4 tAzx
Example 2.2.4. The Benjamin-Bona-Mahony (BBM) Equation
Consider the simplified BBM equation [239] in the form
.0 txxxxt uauuuu (2.84)
The Benjamin-Bona-Mahony equation (2.84) possesses precisely three sovereign and
non-trivial conservation laws [36]. If we put 1 vu in (2.84) with 1a , we get an
equivalent equation:
.xtxxt vvvv (2.84a)
The three conservation laws for the equation (2.84a) are:
,02
1 2
x
txt vvv (2.84b)
,03
1
2
1
2
1 322
x
tx
t
x vvvvv (2.84c)
.04
1
3
1 42223
x
txtxt
t
vvvvvv (2.84d)
Using the wave variable (1.8) in (2.84) that converts the given partial differential
equation into an ordinary differential equation and upon integrating once with integration
constant zero capitulates
.02
1)1( 2 aVuuuV (2.85)
Taking into consideration the balancing principle between the terms u and 2u in (2.85),
we deduce that .2n Therefore, the trial solution can be written as
.)( 012
G
G
G
Gu (2.86)
Substituting (2.86) and (2.5) in (2.85), following polynomial in G as follows:
64
.02
1
2
1
2
1
28
42
1
62
116
2
1
28242
1
21200
202
22220
1211011
121/
1213
22222
2120
2
22
222
212202
222
4
222
622
222
8
ppVpppV
pVGG
qVaqGGrVarGG
qqVpqVapqqqG
qVaprrVrrrprVaqG
rVaqrGrVarG
(2.87)
Proceeding as before and solving (2.87), the two solution sets are obtained as follows:
Set 1.
,116
482
ap
a ,01 ,
116
480
ap
ap ,0q ,
116
1
apV (2.88)
where p and a are arbitrary constant.
Set 2.
,116
482
ap
a ,01 ,
116
160
ap
ap ,0q ,
116
1
apV (2.89)
where p and a are arbitrary constant.
,116
48
116
48)(
ap
ap
G
G
ap
au (2.90)
where .116
1t
apx
The ensuing families of exact solutions due to step 3 of section 1.5.1 are:
Family 1. If ,0p ,0 the form of the solution is
2
1
)2cosh(
2)(
qp
pG
.
65
Because ,0q then .0r In this case the ratio is
)2tanh( ppG
G
.
Consequently, the obtained wave solution is
).2(sec116
48)( 2 ph
ap
apu
(2.91)
Family 2. If ,0p ,0 the form of the solution is
2
1
)2sinh(
2)(
qp
pG
.
Because ,0q then .0r In this case the ratio is
)2coth( ppG
G
.
Consequently, wave solution is
).2(csc116
48)( 2 ph
ap
apu
(2.92)
Family 3. If ,0p ,0 the form of the solution is
2
1
)2cos(
2)(
qp
pG
or
2
1
)2sin(
2)(
qp
pG
.
Because ,0q then .0r Thus the ratio is
)2tan( ppG
G
or )2cot( pp
G
G
.
Consequently, the wave solution is
)2(sec116
48)( 2 p
ap
apu
or ).2(csc
116
48)( 2 p
ap
apu
(2.93)
Family 4. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
66
Because ,0q and the ratio in this case is
)coth()tanh(2
1 ppp
G
G
or )(csc
2
2 phr
p
G
G
.
Consequently, the wave solution is
116
48)coth()tanh(
116
12)(
2
ap
appp
ap
apu
or
.116
48)(csc
116
12)( 4
2
ap
apph
apr
apu (2.94)
Family 5. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
Because 0q the ratio in this case is
)tan()cot(2
1 ppp
G
G
.
Consequently, the obtained solution is
.116
48)]tan()([cot
116
12)( 2
ap
appp
ap
apu (2.95)
Family 6. If ,0p ,0q the form of the solution is
2
1
)4exp(641
)2exp()(
prp
ppG .
Then the ratio is
rrG
G
4coth
8
1 ,
where 164 rp .
Consequently, the following traveling wave solution is
,116
48
4coth
1164
3)( 2
ap
ap
rapr
au
(2.96)
67
where .116
1t
apx
Similarly other solutions of the BBM equation can be found as well.
The trial solution for the set 2 becomes
,
116
16
116
48)(
ap
ap
G
G
ap
au
(2.97)
where .116
1t
apx
The succeeding families of exact solutions due to step 3 of section 1.5.1 are
Family 7. If ,0p ,0 the form of the solution is
.)2cosh(
2)(
2
1
qp
pG
Because ,0q .0r The ratio in this case is
)2tanh( ppG
G
.
Consequently, the wave solution is
.116
162tanh
116
48)( 2
ap
app
ap
apu (2.98)
Family 8. If ,0p ,0 the form of the solution is
2
1
)2sinh(
2)(
qp
pG
.
Because ,0q so .0r The ratio in this case is
).2coth( ppG
G
Consequently, the solution is
.116
16)2(coth
116
48)( 2
ap
app
ap
apu (2.99)
68
Family 9. If ,0p ,0 the form of the solution is
2
1
)2cos(
2)(
qp
pG
or
2
1
)2sin(
2)(
qp
pG
.
Because ,0q then .0r Thus the ratio is
)2tan( ppG
G
or )2cot( pp
G
G
.
Consequently, the traveling wave solution is
116
16)2(tan
116
48)( 2
ap
app
ap
apu
or .116
16)2(cot
116
48)( 2
ap
app
ap
apu (2.100)
Family 10. If ,0p ,0r the form of the solution is
Because ,0q so in this case the ratio is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
Consequently, the wave solution is
116
16)]coth()tanh([
116
12)( 2
ap
appp
ap
apu
or
.116
16)(csc
116
12)( 4
2
ap
apph
apr
apu (2.101)
Family 11. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
69
Because ,0q so in this case the ratio is
)tan()cot(2
1 ppp
G
G
.
Consequently, the traveling wave solution is
.116
16)]tan()([cot
116
12)( 2
ap
appp
ap
apu (2.102)
Family 12. If ,0p ,0q the form of the solution is
.)4exp(641
)2exp()(
2
1
prp
ppG
Then the ratio is
,4
coth8
1
rrG
G
where 164 rp .
Consequently, the traveling wave solution is
,116
16
4coth
1164
3)( 2
ap
ap
rapr
au
(2.103)
where .116
1t
apx
Now solving (2.84) by using extended tanh-function method. The solution of the (2.85)
can be represented as
,)()()( 012
2 u (2.104)
where )( satisfy the Riccati equation
).()( 2 A (2.105)
Substituting (2.104) and (2.105) into (2.85), following polynomial equation in is
obtained as follows
70
.02
12)()2(
)()2
18(
)()2()()2
16(
202
20010111
22022
212
3211
4222
aVAVVaVA
VaVA
aVaV
(2.106)
Proceeding as before, the following two solution sets are obtained as;
Set 3.
,14
122
aA
a ,01 ,
14
40
aA
aA .
14
1
aAV (2.107)
Set 4.
,14
122
aA
a ,01 ,
14
120
aA
aA ,
14
1
aAV (2.108)
where A and a are arbitrary constants.
So, the exact solutions of (2.84) for the solution set 3 are:
When 0A , the form of the solution is
14
4)(tanh
14
12)( 2
aA
aAA
aA
aAu
or .14
4)(coth
14
12)( 2
aA
aAA
aA
aAu (2.109)
When 0A , the form of the solution is
14
4)(tan
14
12)( 2
aA
aAA
aA
aAu
or ,14
4)(cot
14
12)( 2
aA
aAA
aA
aAu (2.110)
where .14
1t
aAx
And, the exact solutions of (2.84) for the solution set 4 are:
When 0A , the form of the solution is
14
12)(tanh
14
12)( 2
aA
aAA
aA
aAu
71
or .14
12)(coth
14
12)( 2
aA
aAA
aA
aAu (2.111)
When 0A , the form of the solution is
14
12)(tan
14
12)( 2
aA
aAA
aA
aAu
or ,14
12)(cot
14
12)( 2
aA
aAA
aA
aAu (2.112)
where .14
1t
aAx
Example 2.2.5. The Symmetric Regularized Long Wave Equation
Consider the following SRLW equation [195],
,0 xxtttxxtxxtt uuuuuuu (2.113)
this equation occurs in numerous physical applications like ion sound waves in plasma.
This equation is symmetrical with respect to x and t.
Using the traveling wave variable (1.8) into (2.113) and integrating twice with integration
constants zeros yields
.02
11 222 uVuVuV (2.114)
Taking into consideration the balancing principle between the terms u and 2u in (2.114),
we deduce that .2n Thus, the trial solution is
.//)( 01
2
2 GGGGu (2.115)
Substituting (2.115) together with (2.5) into (2.114), the following polynomial equation
in G is obtained as follows:
72
.02
1
2
1
2
1
2
8)4
2
1()6
2
1
2
116(
)28()2
124(
21200
2202
2222
20
12110121
2112
21123
22
2022
22
212
222
2212
22220
222
22
24
222
26222
22
28
pVpVVVppVpV
pVVVGGqVqVGG
rVrVGGpqVqVqV
pqVqVqGqVrVr
qVrVprVrVprVG
qrVrqVGrVrVG
(2.116)
Proceeding as before the two solution sets are obtained;
Set 1.
.161
1,0,
161
48,0,
161
48012
piVq
p
pi
pi
(2.117)
Set 2.
.161
1,0,
161
16,0,
161
48012
piVq
p
pi
pi
(2.118)
The form of the trial solution for the set 1 becomes
,161
48/
161
48)(
2
p
piGG
piu
(2.119)
where ,161
1t
pix
while the form of the trial solution for the set 2 becomes
,161
16/
161
48)(
2
p
piGG
piu
(2.120)
where .161
1t
pix
According to the step 3 of section 1.5.1, the following subsequent families of exact
solutions are obtained as follows:
73
Family 1. If ,0p ,0 the form of the solution is
2
1
)2cosh(
2)(
qp
pG
.
Because ,0q then .0r The ratio in this case is
)2tanh( ppG
G
.
Consequently, the traveling wave solutions are;
,161
482tanh
161
48)( 2
p
pip
p
piu
(2.121)
and for set 2, the solution is
.161
162tanh
161
48)( 2
p
pip
p
piu
(2.122)
Family 2. If ,0p ,0 the form of the solution is
2
1
)2sinh(
2)(
qp
pG
.
Because ,0q then .0r The ratio in this case is
ppG
G2coth
.
Consequently, the traveling wave solution for the set 1 is
,161
482coth
161
48)( 2
p
pip
p
piu
and for the set 2 is
.161
162coth
161
48)( 2
p
pip
p
piu
(2.124)
74
Family 3. If ,0p ,0 the form of the solution is
2
1
)2cos(
2)(
qp
pG
or
2
1
)2sin(
2)(
qp
pG
.
Since ,0q then .0r Thus the ratio is
)2tan( ppG
G
or )2cot( pp
G
G
.
Consequently, traveling wave solution for the set 1 is
p
pip
p
piu
161
482tan
161
48)( 2
or ,161
482cot
161
48)( 2
p
pip
p
piu
(2.125)
and for the set 2 is
p
pip
p
piu
161
162tan
161
48)( 2
or .161
162cot
161
48)( 2
p
pip
p
piu
(2.126)
Family 4. If ,0p ,0r the form of the solution is
2
1
2
)tanh(2
)(sec)(
prpq
phpG or
2
1
2
)coth(2
)(csc)(
prpq
phpG .
Because ,0q so in this case the ratio is
)coth()tanh(2
1 ppp
G
G
or )(csc
2
2 phr
p
G
G
.
Consequently, the traveling wave solutions for the set 1 is
p
pipp
p
piu
161
48)coth()tanh(
161
12)(
2
75
or ,161
48)(csc
161
12)( 4
2
p
piph
pr
piu
(2.127)
and for the set 2 is
p
pipp
p
piu
161
48)coth()tanh(
161
12)(
2
or .161
48)(csc
161
12)( 4
2
p
piph
pr
piu
(2.128)
Family 5. If ,0p ,0r the form of the solution is
2
1
2
)tan(2
)(sec)(
prpq
ppG or
2
1
2
)cot(2
)(csc)(
prpq
ppG .
Because ,0q so in this case the ratio becomes
)tan()cot(2
1 ppp
G
G
.
Consequently, the traveling wave solution for the set 1 is
,161
48)tan()cot(
161
12)(
2
p
pipp
p
piu
(2.129)
and for the set 2 is
.161
48)tan()cot
161
12)(
2
p
pipp
p
piu
(2.130)
Family 6. If ,0p ,0q the form of the solution is
2
1
)4exp(641
)2exp()(
prp
ppG .
The ratio in this case is
rrG
G
4coth
8
1 ,
where 164 rp .
76
Consequently, the traveling wave solution for the set 1 is
,161
48
4coth
1614
3)( 2
p
pi
rpr
piu
(2.131)
and for the set 2 is
,161
48
4coth
1614
3)( 2
p
pi
rpr
piu
(2.132)
where .161
1t
pix
Now solving (2.113) by using extended tanh-function method. The solution of (2.113)
can be represented as:
,)()()( 012
2 u (2.133)
where )( satisfy the Riccati equation,
).()( 2 A (2.134)
Substituting (2.133) and (2.134) into (2.114), the following polynomial is obtained:
.02
12
)()2(
)()2
18(
)()2()()2
16(
202
220
20
1012
112
22022
212
2
3211
24222
2
VAVV
VVAV
VVVAV
VVVV
(2.135)
Proceeding as before, the two sets of solution are obtained as follows;
Set 3.
.41
1,
41
4,0,
41
12012
AiV
A
Ai
Ai
(2.136)
Set 4.
.41
1,
41
12,0,
41
12012
AiV
A
Ai
Ai
(2.137)
77
Thus, the exact solution of (2.113) for the solution set 3 have the following forms:
A
AiA
A
Aiu
41
4)(tanh
41
12)( 2
or .,41
4)(coth
41
12)( 2
A
AiA
A
Aiu
(2.138)
and for the solution set 4 for 0A
A
AiA
A
Aiu
41
12)(tanh
41
12)( 2
or .41
12)(coth
41
12)( 2
A
AiA
A
Aiu
(2.139)
For the solution set 3, when 0A the form of the solution is
A
AiA
A
Aiu
41
4)(tan
41
12)( 2
or .,41
12)(cot
41
12)( 2
AiA
A
Aiu
(2.140)
while for the solution set 4 for 0A
A
AiA
A
Aiu
41
12)(tan
41
12)( 2
or ,41
12)(cot
41
12)( 2
A
AiA
A
Aiu
(2.141)
where .41
1t
Aix
Discussion
Lately, the observation on the equivalence of results obtained by using extended tanh-
function method introduced by Fan [58] and original )/( GG -expansion method
introduced by Wang et al. [217] has been given by Parkes [187]. The same observation
has been pointed out by Kudryashov [113]. The results obtained by further improved
)/( GG -expansion method presented in this chapter have been compared with those
obtained by extended tanh-function method. From this study, it is observed that further
improved )/( GG -expansion method and extended tanh-function methods are not
78
equivalent. All the results obtained by extended tanh-function method are found by
further improved )/( GG -expansion method, when the parameters are given some
specific values. Similarly, some new solutions are also obtained.
79
Chapter 3
Soliton Solutions of Nonlinear Evolution Equations
by Improved )/( GG -Expansion Method
80
3.1. Introduction
The nonlinear evolution equations (NLEEs) are widely used as models to describe
complex physical phenomena in various fields of sciences, especially in fluid mechanics,
plasma waves and biology. One of the basic physical problems for those models is to
obtain their traveling wave solutions. Various techniques have been specifically used to
unearth different kinds of solutions of physical models described by nonlinear PDEs.
Stability and convergence must be considered in numerical methods [40, 67, 89] to avoid
divergent or inappropriate results. Several effective analytical and semi analytical
methods, including Homotopy Perturbation [72], Parameter Expansion [69], Extended
Tanh-Function [223] and Series Expansion [248, 249] methods have been developed
considerably to tackle nonlinear partial differential equations.
To dilate the possibility of applications, effectiveness and trustworthiness of the )/( GG -
expansion method, several researchers studied various nonlinear PDEs to generate
traveling wave solutions via improved )/( GG -expansion method and can be found in
[24, 262, 263]. Shehata [204] also modified the basic )/( GG -expansion method to
derive traveling wave solutions for nonlinear Schrodinger equation and the cubic-quintic
Ginzburg Landau equation. Zhang [274] explored a new application of this method to
some special nonlinear evolution equations, the balance numbers of which are not
positive integers. Recently, Liu et al. [126] proposed a new modification of traditional
)/( GG -expansion method to seek the traveling wave solution of NLEEs. In this
modified version the second order nonlinear ordinary differential equation
,22 GCGBGGAGG
is used as an auxiliary equation.
The transformed rational function method used by Ma [130, 132] and the basic )/( GG -
expansion method introduced by Wang et al. [217] have a common idea, i.e. to put the
given NLEE into the corresponding ordinary differential equation (ODE), then the ODE
can be transformed into a system of algebraic polynomials with the determining
constants. The exact traveling wave and rational solutions of the NLEE can be obtained
by the solutions of the ODE, however, the linear superposition principle [131] and
multiple exp-function method [144] is applierd to get the N-soliton and N-wave solution
81
of the PDE. Furthermore, improved )/( GG -expansion method handles NLEEs in a
direct manner with no initial/boundary conditions requirement.
In this chapter, an improved )/( GG -expansion method has been utilized to construct the
traveling wave solutions of nonlinear evolution equations [39, 167, 197].
3.2. Numerical Examples
In this section, some examples to elaborate the efficiency of the well known technique,
improved )/( GG -expansion method is discussed. The proposed method is effective,
reliable and credible. Several examples are given to illustrate the reliability and
performance of the projected scheme.
Example 3.2.1. The Burgers Equation
Consider the following Burgers equation [197] in the following form
.0 xxxt uuuu (3.1)
The applications of the Burgers equation can be found in applied mathematics, such as
modelling of fluid dynamics, turbulence, shock wave formation and traffic flow.
Making use of the wave transformation (1.8) into (3.1) gives
.0 uuuuV (3.2)
After integrating (3.2) and setting the integration constant as zero yields
.02
1 2 uuuV (3.3)
Considering the homogeneous balance between u and ,2u we deduce that 1M .
Therefore, according to step 2 of section 1.4.3, the trial solution (1.23) turns out to be
,0,)(
)()( 110
G
Gu (3.4)
where 0 and 1 are constants and need to be determined. Substituting (3.4) along with
(1.24) into (3.3), a system of equations in iGG )/( is obtained. A set of algebraic
82
equations with respect to unknowns is obtained by setting each coefficient of
2,1,0,)/( iGG i equal to zero
.02
1:/
,0:/
,02
1:/
2111
2
1101
1
2010
0
CGG
BVGG
AVGG
(3.5)
Solving the system of equations (3.5); two sets of solution are obtained as follows:
Set 1.
.12,44,44 12
02 CACABBACABV (3.6)
Set 2.
.12,44,44 12
02 CACABBACABV (3.7)
Substituting (3.6) and (3.7) into (3.4) and according to (1.25)- (1.28), three types of the
solutions of (3.1) are obtained as
Case 1. When 0B
and ,04421 ACAB then the exponential function
solutions can be found as
.1),(
22
21
22
21
111
11
tVxtVx
tVxtVx
ecec
ecectxu (3.8)
Case 2. When 0B
and ,04421 ACAB then the triangular function
solutions will be
.
2cos
2sin
2sin
2cos
1),(1
2
1
1
1
2
1
1
1
tVxctVxic
tVxctVxictxu (3.9)
Case 3. If 0B and 0)1(2 CA , then the triangular function solutions are
.cossin
sincos1),(
2221
22212
tVxctVxc
tVxctVxctxu (3.10)
83
Case 4. Again, if 0B and ,0)1(2 CA then the hyperbolic function solutions are:
,coshsinh
sinhcosh1),(
2221
22212
tVxctVxci
tVxctVxcitxu (3.11)
where A, B, C and 21 , cc are real parameters.
In particular, if ,21 cc (3.8) becomes,
.2
tanh1),( 11
tVxtxu (3.12)
Again, at ,21 cc (3.8) becomes
.2
coth1),( 11
tVxtxu (3.13)
Similarly, other solutions from cases 2-4 are obtained as well by giving particular values
to 1c and .2c
Example 3.2.2. The Zakharov-Kuznetsov (ZK) Equation
Consider the ZK equation [197] in two spatial and one time, dimensions presented as
,0xyyxxxt uubuuau (3.14)
where a and b are constants. Poole [190] showed that ZK equation (3.14) is not
completely integrable, as it does not pass any conventional integrability test like, the
inverse scattering transform and Painleve property. The three conservation laws for the
equation (3.14) are:
,02
2
yxyxxxt buDbuu
aDuD (3.14a)
,0223
2 2232
yxyyyxxyxxt ubuDuubuuubu
aDuD (3.14b)
84
.06
3
6
36
43
3
22
2
222
2222
223
yyxxxyxyy
yyyxxyyxyyxxxx
yyxxyxxx
xyxt
uuua
bubuD
uuuuuua
b
uua
buububuu
au
Duua
buD
(3.14c)
The equation (3.14) is converted into an ODE upon using the wave variable (1.8)
.022
2
ubua
uV (3.15)
Integrating (3.15) and neglecting integration constant yields
.022
2 ubua
uV (3.16)
Considering the homogeneous balance between u and ,2u we get ,22 MM i.e.
2M . Therefore, according to step 2 of section 1.4.3, the trial solution (1.23) turns out
to be
,0,)(
)(
)(
)()( 2
2
210
G
G
G
Gu (3.17)
where ,0 1 and 2 are constants and need to be dogged later. Inserting (3.17) along
with (1.24) into (3.16), a system of equations in iGG )/( is obtained as follows
85
.0242
11212:/
,04
820420:/
,0616
862
116:/
,0412
24:/
,0242
1:/
2222
22
4
2121
1212
3
12122
221
212
2
12
102
111
1
12
2200
0
CbabCbGG
Cba
CbBbbBCbGG
BbaVAb
BbBCbaACbGG
AbABb
aBbACbVGG
ABbAbaVGG
(3.18)
Proceeding as before the following two solution sets are obtained as follows;
Set 1.
.
124,
124
,124
,442
2
21
02
a
Cb
a
CbB
a
CbABACAbV
(3.19)
Set 2.
,
224,442
2
02
a
BACAbBACAbV
.
124,
1242
21a
Cb
a
CbB
(3.20)
Substituting (3.19) and (3.20) into (3.17) and according to equations (1.25)- (1.28), the
solutions for different cases are
Case 1. When 0B
and ,04421 ACAB then the exponential function
solutions can be found as
.
6),,(
2
22
21
22
2111
11
11
tVyxtVyx
tVyxtVyx
ecec
ecec
a
b
a
btyxu
(3.21)
Case 2. When 0B
and ,04421 ACAB the triangular function solution will be
86
.
2cos
2sin
2sin
2cos
6),,(
2
1
2
1
1
1
2
1
111
tVyxctVyxic
tVyxctVyxic
a
b
a
btyxu
(3.22)
Case 3. If 0B and 0)1(2 CA , then the triangular function solutions is
.cossin
sincos244),,(
2
2221
222122
tVyxctVyxc
tVyxctVyxc
a
b
a
btyxu
(3.23)
Case 4. Again, if 0B and 0)1(2 CA , the hyperbolic function solutions is
,4
coshsinh
sinhcosh24),,(
2
2
2221
22212
a
b
tVyxctVyxic
tVyxctVyxic
a
btyxu
(3.24)
where A, B, C and 21 , cc are real parameters and a, b are positive constants. equals to
2 or 6, so is . And if equals to 2, choose 2442 BACAbV and if equals to 6,
then V is 2442 BACAb . Similarly, if is equal to 2 or 6, V is
2442 BACAb or 2442 BACAb respectively.
As a special case, if 01 c and ,02 c then (3.23) becomes
.cot244
),,( 2222 tVyx
a
b
a
btyxu
(3.25)
And (3.24) becomes
.coth244
),,( 2222 tVyx
a
b
a
btyxu
(3.26)
Similarly, if 01 c and ,02 c then (3.23) becomes
.tan244
),,( 2222 tVyx
a
b
a
btyxu
(3.27)
And (3.24) becomes
.tanh244
),,( 2222 tVyx
a
b
a
btyxu
(3.28)
87
Similarly, the other solutions of (3.14) can be work out as well by giving particular
values to 1c and .2c
Example 3.2.3. The Boussinesq Equation
Now, consider the (1 + 1)-dimensional Boussinesq equation [197] in the form,
.02 xxxxxxxxtt uuuu (3.29)
This equation was proposed by Boussinesq for a model of nonlinear dispersive waves. It
explains the propagation of long waves in shallow water. Due to the existence of an
infinite number of conservation laws and N-soliton solutions, the Boussinesq equation
[80] is considered as completely integrable.
Equation (3.29) is converted into an ordinary differential equation upon using (1.21) and
integrating yields
,01 22 uuuV (3.30)
with constant of integrations are considered as zeros. Now,
balancing u and ,2u we
deduced that 2M . Therefore, the trial solution (1.23) becomes
,0,)(
)(
)(
)()( 2
2
210
G
G
G
Gu (3.31)
Inserting (3.31) along with (1.24) into (3.30), the following system of algebraic equations
in )/( GG is obtained as
.012266:/
,026410210:/
,0368
4338:/
,026
62:/
,023:/
2222
22
4
21211212
3
1202
221
21222
22
12
102
111121
12
22000
20
CCGG
CCBBCGG
BA
BBCACVGG
AAB
BACVGG
ABAVGG
(3.32)
88
Solving the above set of algebraic equations, two solution sets are obtained as follows;
Set 1.
.12,12,12,4142
2102 CCBCAABCAV (3.33)
Set 2.
.16,16,22,4142
212
02 CCBABACABCAV (3.34)
Substituting (3.33) and (3.34) in (3.31) and according to (1.25)- (1.28), the solutions of
(3.29) as:
Case 1. When 0B
and ,04421 ACAB the exponential function solution
will be
.
2
3
2),(
2
22
21
22
2111
11
11
tVxtVx
tVxtVx
ecec
ecectxu
(3.34)
Case 2. When 0B
and ,04421 ACAB then the triangular function solution
will be
.
2cos
2sin
2sin
2cos
2
3
2),(
2
12
11
1
2
1
111
tVxctVxic
tVxctVxictxu
(3.35)
Case 3. If 0B and 0)1(2 CA , then the triangular function solution is
.cossin
sincos62),(
2
2221
2221
22
tVxctVxc
tVxctVxctxu (3.36)
Case 4. Again, if 0B and 0)1(2 CA , then the hyperbolic function solution is
,coshsinh
sinhcosh62),(
2
2221
2221
22
tVxctVxic
tVxctVxictxu (3.37)
89
equals to 1 or 3, so is . And if equals to 1, then ABCAV 414 2 , if
equals to 3, then ABCAV 414 2 . Similarly, if is equal to 1 or 3, then
ABCAV 414 2 or ABCAV 414 2 respectively.
In particular, if ,21 cc then (3.34) becomes
,2
coth2
3
2),(
2
111
tVxtxu
(3.38)
and, if ,21 cc then (3.34) becomes
.2
tanh2
3
2),(
2
111
tVxtxu
(3.39)
Similarly, the other solutions of (3.29) can be found as well by giving particular values to
1c and 2c for cases (2-4).
Example 3.2.4. The Coupled Higgs Equations
Consider the following Higgs field equation [269] in the form
,0)(
,02
2
2
xxxxtt
xxtt
ubvv
uvuubauuu (3.40)
where for 0,0 ba the equation (3.40) is called the coupled Higgs field equation.
Here, by choosing ,1,0 ba (3.40) reduces to the following coupled Higgs field
equation
,0)(
,02
2
2
xxxxtt
xxtt
uvv
uvuuuu (3.40a)
By introducing a complex wave variable rtpxVtxWveUu i ,,,
that transforms (3.40a) into an ODE as follows
,0221
,02122
3222
UUUWVV
UWUUrpUV (3.41)
The second equation in (3.41) is integrating with constant of integration zero yields
(3.42)
90
Substituting (3.42) into the first equation of the system (3.41) yields
.0111 322224 UVUrpVUV (3.43)
Considering the homogeneous balance between U and ,3U we get 1M . Therefore, the
trial solution (1.23) becomes,
,0,)(
)()( 110
G
GU (3.44)
where 0 and 1 are constants and need to be determined. Substituting (3.44) along
with (1.24) into (3.43) yields a system of equations in .)/( iGG Setting each coefficient
of same power of )3,2,1,0(,)/( iGG i to zero, a system of algebraic equations with
respect to unknowns ,0 1 is obtained as follows
.024
4222:/
,0333333:/
,0223
223:/
,0
:/
21
41
14
143
122
113
1
3
1102
12
14
14
02
1
2
21
41
2211
41
2201
2
112
12
14
1201
221
30
210
2
14
02
022
0223
0
0
CVC
CcVVCGG
BCBVBCVBVGG
BVpVAAVBV
CArpCAVrVGG
cBAr
BAVprVpcGG
(3.45)
Solution of (3.45) gives
),1(44
12,44
1,44
)(21
2
22
12
22
02
22
C
ACAB
rpiB
ACAB
rpi
ACAB
rpV (3.46)
Substituting (3.46) in (3.44) and according to (1.25)- (1.28), the following solutions of
the coupled Higgs equation (3.40a) are obtained as follows:
Case 1. When 0B
and ,04421 ACAB the exponential function solutions
can be found as:
,
expexp
expexp1
121
2121
1
121
2121
1
1
22
11
cc
ccrpiU
91
,
expexp
expexp
2
2
121
2121
1
121
2121
111
cc
ccW
,exp
expexp
expexp1
121
2121
1
121
2121
1
1
22
11 rtpxicc
ccrpiu
.
expexp
expexp
2
2
121
2121
1
121
2121
111
cc
ccv
(3.47)
Case 2. When 0B
and ,04421 ACAB then the triangular function solutions
will be:
,
cossin
sincos1
121
2121
1
121
2121
1
1
22
12
cic
cicrpiU
,
cossin
sincos
2
2
121
2121
1
121
2121
112
cic
cicW
,expcossin
sincos1
121
2121
1
121
2121
1
1
22
12 rtpxicic
cicrpiu
.
cossin
sincos
2
2
121
2121
1
121
2121
112
cic
cicv
(3.48)
Case 3. If 0B and 0)1(2 CA , then the triangular function solutions are:
,cossin
sincos
412
2221
2221
2
22
23
cc
ccrpiU
,cossin
sincos2
2
2221
2221
23
cc
ccW
,expcossin
sincos
412
2221
2221
2
22
23 rtpxicc
ccrpiu
.cossin
sincos2
2
2221
2221
23
cc
ccv (3.49)
92
Case 4. Again, if 0B and 0)1(2 CA , then the hyperbolic function solutions
are:
,coshsinh
sinhcosh
412
2221
2221
2
22
24
cic
cicrpiU
,coshsinh
sinhcosh2
2
2221
2221
24
cic
cicW
,expcoshsinh
sinhcosh
412
2221
2221
2
22
24 rtpxicic
cicrpiu
,coshsinh
sinhcosh2
2
2221
2221
24
cic
cicv (3.50)
,12
tanh12,22
21
t
rpxcitxU
,12
tanh2,22
21
t
rpxtxW
,exp12
tanh12,22
21 rtpxit
rpxcitxu
.12
tanh2,22
21
t
rpxtxv (3.51)
Also, if 21 cc and ,4
1 and1,1 CBA then (3.47) becomes
93
,12
coth12,22
21
t
rpxcitxU
,12
coth2,22
21
t
rpxtxW
,exp12
coth12,22
21 rtpxit
rpxcitxu
.12
coth2,22
21
t
rpxtxv (3.52)
Similarly, other solutions of coupled Higgs equations (3.40a) for cases (2-4) can be found
as well.
Example 3.2.5. The Maccari System
Now, consider the Maccari system [167] in the form
.0)(
,02
xyt
xxt
uvv
uvuiu (3.53)
By introducing a wave variable ,,,, rtqypxVtyxWveUu i
that converts (3.53) into an ordinary differential equations as
.021
,02
UUWV
WUUprU (3.54)
Integrating the system (3.54) and neglecting the constant of integration yiels
.1 2UWV (3.55)
Inserting (3.55) into the first equation of (3.54) yields
.011 32 UUprVUV (3.56)
Considering the homogeneous balance between U and 3U in (3.56), we get 1M .
Therefore, the trial solution (1.23) becomes
.0,)(
)()( 110
G
GU (3.57)
94
Inserting (3.57) and (1.24) into (3.56), yields a system of equations in .)/( iGG Setting
each coefficient of same power of )3,2,1,0()/( iGG i to zero, the following system
of algebraic equations with respect to unknowns ,0 1 is obtained
.0242422:/
,033333:/
,023
222:/
,0:/
21111
31
211
3
112
1011
2
12
11201
211
211111
21
300
200110
20
CCVVCCVGG
BCVBCBBVGG
rBCA
BVVpACAVAVVrpGG
prVrBABAVVpGG
(3.58)
Solving the above system (3.58), the obtained solution is
),1(12,122
1,44
2
110
22 CVBVpCAABV (3.59)
Substituting (3.59) into (3.57) and according to (1.25)- (1.28), the solutions of (3.53) are
Case 1. When 0B
and ,04421 ACAB the exponential function solutions
can be found as
,
expexp
expexp12
2
1
121
2121
1
121
2121
1
11
cc
ccVU
,
expexp
expexp
2
2
121
2121
1
121
2121
111
cc
ccW
,442
1exp
expexp
expexp12
2
1
22
121
2121
1
121
2121
1
11
tpCAABqypxi
cc
ccVu
.
expexp
expexp
2
2
121
2121
1
121
2121
111
cc
ccv
(3.60)
95
Case 2. When 0B
and ,04421 ACAB then the triangular function solutions
will be
,
cossin
sincos12
2
1
121
2121
1
121
2121
1
12
cic
cicVU
,
cossin
sincos
2
2
121
2121
1
121
2121
112
cic
cicW
,442
1exp
cossin
sincos12
2
1
22
121
2121
1
121
2121
1
12
tpCAABqypxi
cic
cicVu
.
cossin
sincos
2
2
121
2121
1
121
2121
112
cic
cicv
(3.61)
Case 3. If 0B and 0)1(2 CA , then the triangular function solutions are
,cossin
sincos12
2221
2221
23
cc
ccVU
,cossin
sincos2
2
2221
2221
23
cc
ccW
,12exp
cossin
sincos12
2
2221
2221
23
tpCAqypxi
cc
ccVu
,cossin
sincos2
2
2221
2221
23
cc
ccv
(3.62)
Case 4. Again, if 0B and 0)1(2 CA , the hyperbolic function solutions are
,coshsinh
sinhcosh12
2221
2221
24
cic
cicVU
,coshsinh
sinhcosh2
2
2221
2221
24
cic
cicW
96
,12exp
coshsinh
sinhcosh12
2
2221
2221
24
tpCAqypxi
cic
cicVu
,coshsinh
sinhcosh2
2
2221
2221
24
cic
cicv (3.63)
where .442
1 22 tpCAAByx
In particular, if 21 cc and ,4
1 and1,1 CBA then (3.60) becomes:
,tanh12,,1 tVyxVtyxU
,tanh2,, 21 tVyxtyxW
,2exptanh12,, 221 tpqypxitVyxVtyxu
.tanh2, 21 tVyxtxv (3.64)
Also, if 21 cc and ,4
1 and1,1 CBA then (3.60) becomes:
,coth12,,1 tVyxVtyxU
,coth2,, 21 tVyxtyxW .
,2expcoth12,, 221 tpqypxiVtyxVtyxu
.coth2, 21 tVyxtxv (3.65)
Similarly, other solutions of the Maccari system (3.53) for cases (2-4) can be calculated
as well.
Example 3.2.6. The Fifth Order Caudrey-Dodd-Gibbon Equation
Finally, consider the fifth order CDG equation [39] in the form
.01803030 2 xxxxxxxxxxxxt uuuuuuuu (3.66)
This equation play an important part in numerous scientific applications such as solid
state physics, nonlinear optics, mathematical biology, nonlinear optics and quantum field
97
theory. The fifth order CDG equation [42] belongs to the class of completely integrable
equations and therefore, the conservation laws for the ranks 3, 4 and 6 are as follows
.57636002045763242
,144014405400108481224
252792184864
48963622
,12180
,2161803606
48367222
,2
623422
232
23
243
62
42324
33
2
222
22
42
3232
23425
2453624
42224
52
3224
2
222
23234233
323
uuuuuuuuuuT
uuuuuuuuuuu
uuuuuuuuuuu
uuuuuuuuuuuuuX
uuuuT
uuuuuuu
uuuuuuuuuuuuX
uuT
xxxxxx
xxxxxx
xxxxxxxxx
xxxxxxxxxx
xx
xxx
xxxxxxxxxx
x
(3.66a)
Using the wave variable (1.8) that carries (3.66) into an ODE as
.01803030 25 uuuuuuuuV (3.67)
Integrating (3.67) and with constant of integration zero yields
.06030 34 uuuuuV (3.68)
Now, balancing )4(u and ,3u we get 2M . Therefore, the trial solution (1.23) becomes
.0,)( 2
2
210
G
G
G
Gu (3.69)
Inserting (3.69) along with (1.18) into (3.68) yields a system of equations in
.)/( iGG Setting each coefficient of same power of )3,2,1,0()/( iGG i to zero, a
system of algebraic equations (which are omitted here for the sake of simplicity) with
respect to unknowns 0 , 1 , 2 and V is obtained and after solving the system yields the
following solution
.)1(,1,1
,168328162
210
2242222
CCBCA
AABBCAACBACV
(3.70)
98
Substituting (3.70) into (3.69) and according to (1.25)- (1.28), the solutions of the fifth
order Caudrey-Dodd-Gibbon (CDG) equation (3.66) are as follows:
Case 1. When 0B
and ,0442 ACAB then the exponential function solution
can be found as:
.14
),(
2
22
21
22
21
ecec
ecectxu (3.71)
Case 2. When 0B
and ,0442 ACAB then the triangular function solution
will be
.
2cos
2sin
2sin
2cos
14
),(
2
21
21
cic
cictxu (3.72)
Case 3. If 0B and 0)1( CA , then the triangular function solution will be
.cossin
sincos1),(
2
21
21
cc
cctxu (3.73)
Case 4. Again, if 0B and 0)1( CA , then the hyperbolic function solutions is
,coshsinh
sinhcosh1),(
2
21
21
cic
cictxu (3.74)
where .16832816 2242222 tAABBCAACBACx
In particular, if ,21 cc then (3.71) becomes:
.2
coth14
),( 2
txu (3.75)
99
Fig. 3.1. Represents the form of singular soliton solution of (3.75) for .1 CBA
Again, if ,21 cc then (3.71) becomes:
.2
tanh14
),( 2
txu (3.76)
Fig.3.2. Represents the bell-shaped 2sec h solitary traveling wave solution of (3.76) for ,1,1,1 CBA separated by infinite wings or infinite tails.
Similarly, if ,0,0 21 cc then (3.72) becomes:
.2
tan14
),( 2
txu (3.77)
100
Fig.3.3. Solution (3.77) shows the exact periodic traveling wave solution for .2,1,1 CBA
And, if ,0,0 21 cc then (3.72) becomes:
.2
cot14
),( 2
txu (3.78)
Fig. 3.4. Solution (3.78) explains the soliton for .2,1,1 CBA The particular types of
solitary waves are solitons. The soliton solution is a spatially confined solution, hence, 0)(),(),( uuu as , .tVx
Similarly, other solutions of the fifth order Caudrey-Dodd-Gibbon (CDG) equation (3.66)
for cases (2-4) can be calculated as well.
101
Discussion
In this chapter, an improved )/( GG -expansion method has been used to obtain new
traveling wave solutions of various nonlinear evolution equations. On contrary to basic
)/( GG -expansion method, the benefits of the presented scheme is that all the nonlinear
partial differential equations, which can be solved by basic )/( GG -expansion method,
are easily solved by improved )/( GG -expansion method. Many new and exact
traveling wave solutions have been found. The analysis and computations of the
improved )/( GG method are absolutely resourceful in finding the exact solutions.
102
Chapter 4
Applications of Alternative )/( GG -Expansion Method
with Generalized Riccati Equation
103
4.1. Introduction
The nonlinear differential equations take place in diversified physical phenomena in
science and engineering and many enthusiastic researchers explored the exact solutions
of nonlinear PDEs. There is a widespread category of non-integrable nonlinear
differential equations, which are to some extent integrable because for some values of
parameters these equations become integrable. To gaze for the exact solutions of
nonlinear differential equations, many different methods are used including: Improved F-
Expansion [214], Projective Riccati Equation [233], Hirota [83], Exp-Function [175] and
Homogeneous Balance [276] methods.
Zhu [278] introduced the generalized Riccati equation mapping to solve the (2 + 1)-
dimensional Boiti-Leon-Pempinelle equation. In this generalized Riccati equation
mapping, he employed the following nonlinear ordinary differential equation with
constant coefficients as an auxiliary equation,
.2GqGprG
Li et al. [117] used the Riccati equation expansion method to solve the higher
dimensional NLEEs. Bekir and Cevikel [34] investigated nonlinear coupled equations in
mathematical physics by applying the tanh-coth method, combined with the Riccati
equation. Guo et al. [68] studied the diffusion-reaction and the mKdV equations with
variable coefficients via the extended Riccati equation mapping method. Salas [192] also
used the projective Riccati equation method to obtain some exact solutions for
generalized Sawada-Kotera equation.
Recently, Akbar et al. [25] introduced a new approach of )/( GG -expansion method by
using first order nonlinear ordinary differential equation ,2GqGprG as an
auxiliary equation to construct the traveling wave solutions of fifth-order Caudrey-Dodd-
Gibbon equation. In the subsequent work Zayed [268] also used this method to find the
exact solutions of nonlinear PDEs.
This chapter includes the applications of alternative )/( GG -expansion method in which
generalized Riccati equation is used as an auxiliary equation to construct the soliton
solutions of nonlinear evolution equations [43, 194, 198, 232]. In this method, the
solutions are expressed in terms of trigonometric, hyperbolic, exponential, rational
104
trigonometric, rational hyperbolic and rational exponential functions. This modified
version is very simple and straightforward and gives more general as well as new
solutions as compared to basic )/( GG -expansion method.
4.2. Numerical Examples
In this section, some examples are discussed to elaborate the effectiveness of the well
known technique, alternative )/( GG -expansion method with generalized Riccati
equation. Numerical consequences together with the graphical depiction evidently
divulge the complete trustworthiness and competence of the projected algorithm.
Example 4.2.1. The (1 + 1)-Dimensional Kaup-Kupershmidt Equation
Consider the (1 + 1)-dimensional Kaup-Kupershmidt equation [194] in the form,
.0202510 2 xxxxxxxxxxxxt uuuuuuuu (4.1)
The fifth-order KK equation (4.1), is very important nonlinear partial differential
equation, belongs to the ranking of integrable equations with Lax pair representation. The
KK equation has properties similar to the well-known KdV hierarchy. Physically it
occurs in the promulgation of shallow water and magneto-sound promulgation in
plasmas.
The (1 + 1)-dimensional Kaup-Kupershmidt equation (4.1) [213] divulge the Lax pair
representation as follows:
.21047545309
,22235
3
xxxxxxxxxxx
xxx
uuuuuuuP
uuL
(4.1a)
,0202510 25 uuuuuuuuV (4.2)
where 5u indicates the fifth order derivative with respect to . Integrating (4.2) once
with respect to ,
105
,03
20)(
2
1510 324 uuuuuuVC (4.3)
where C is integration constant. According to step 3 of section 1.4.4, the solution of (4.3)
can be expressed by a polynomial in )/( GG as follows:
,0,...)(2
210
n
n
n aG
Ga
G
Ga
G
Gaau (4.4)
where ia are constants to be indomitable and G gratifies the generalized Riccati equation
.2GqGprG (4.5)
Considering the homogeneous balance between the highest order derivative and the
nonlinear terms in (4.3), we obtain .2n
Therefore, the trial solution takes the form:
.)(2
210
G
Ga
G
Gaau (4.6)
Using (4.5), equation (4.6) can be rewritten as:
.)()()( 212
110 GqGrpaGqGrpaau (4.7)
Substituting (4.7) into (4.3) the following polynomials in iG and iG , ),,3,2,1,0( ni
are obtained. Equating to zero each coefficient of the obtained polynomial, a system of
algebraic equations for rqpaaa ,,,,, 210 and V are obtained.
Solving the over-determined set of algebraic equations, following solution is attained:
.192
1
3
64
8
1122
,16716
,2
3,
2
3,2
8
6334222
2224
21
2
0
pqrqrpqrpC
qrqprp
Vap
arqp
a
(4.8)
Inserting (4.8) into (4.6) the following solution is obtained,
.2
3
2
32
8)(
22
G
G
G
Gprq
pu (4.9)
106
where .16716
2224
tqrqprp
x
Now, on the basis of the solutions of (4.5), the families of exact solutions of (4.1) are:
Family 1. When 042 qrp and ),0or (0 qrqp the solutions are:
,tan2
sec2
2
3
tan2
sec2
2
32
8
222222
1
pp
prq
pu
where ;16716
,42
1 2224
2 tqrqprp
xpqr
qp, and r are arbitrary
constants.
Fig. 4.1. Solution 1u explains the soliton solution corresponding to the parameter values
.2,1,1 rqp Solitons are particular kinds of solitary waves. An amazing chattel of
solitons is that it maintains its individuality upon interacting with other solitons.
,cot2
csc2
2
3
cot2
csc2
2
32
8
222222
2
pp
prq
pu
,22sin22cos
2sin12sec4
2
3
22sin22cos
2sin12sec4
2
32
8
2222
3
pp
prq
pu
,22cos22sin
2cos12csc4
2
3
22cos22sin
2cos12csc4
2
32
8
2222
4
pp
prq
pu
107
,2cos2sin
csc2
2
3
2cos2sin
csc2
2
32
8
2222
5
pp
prq
pu
,2
8
22cos22sin2sin22cos
2sin2sin2cos4
2
3
22cos22sin2sin22cos
2sin2sin2cos4
2
3
2
2
222222
222
222222
222
6
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
,2
8
22cos22sin2sin22cos
2sin2sin2cos4
2
3
22cos22sin2sin22cos
2sin2sin2cos4
2
3
2
2
222222
222
222222
222
7
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
where RBA 0, are constants and gratify the condition 022 BA .
,4cossin4cos22
sin2cossec2
2
3
4cossin4cos22
sin2cossec2
2
32
8
2
222
2
222
22
8
prqp
p
prqp
pprq
pu
,cossin4cos22
cos2sincsc2
2
3
cossin4cos22
cos2sincsc2
2
32
8
2
222
2
222
22
9
pprqp
p
pprqp
pprq
pu
,2cos22sin122cos2
22sin22cos2sin12sec2
2
3
2cos22sin122cos2
22sin22cos2sin12sec2
2
32
8
2
22
2
22
22
10
prqp
p
prqp
pprq
pu
,22sin22sin122cos2
22cos22sin2csc2
2
3
22sin22sin122cos2
22cos22sin2csc2
2
32
8
2
2
2
2
22
11
rqppprq
p
rqppprq
pprq
pu
108
.cossin4cos22
cos2sincsc2
2
3
cossin4cos22
cos2sincsc2
2
32
8
2
222
2
222
22
12
pprqp
p
pprqp
pprq
pu
Family 2. When 042 qrp and ),0or (0 qrqp the soliton-like solutions are:
,tanh2
sec2
2
3
tanh2
sec2
2
32
8
222222
13
p
h
p
hprq
pu
where ;16716
,42
1 2224
2 tqrqprp
xqrp
qp, and r are arbitrary
constants.
,coth2
csc2
2
3
coth2
csc2
2
32
8
222222
14
p
h
p
hprq
pu
,22sinh22cosh
2sinh12sec4
2
3
22sinh22cosh
2sinh12sec4
2
32
8
2222
15
ip
ih
ip
ihprq
pu
,22cosh22sinh
2cosh12csc4
2
3
22cosh22sinh
2cosh12csc4
2
32
8
2222
16
p
h
p
hprq
pu
,2/coth2/tanh12/cosh2
2/sec
2
3
2/coth2/tanh12/cosh2
2/sec
2
32
8
2
2
22
2
222
17
p
h
p
hprq
pu
,
2cosh222sinh2sin
2cosh2sinh4
2
3
2cosh222sinh2sin
2cosh2sinh4
2
32
8
2
22
222
22
2222
18
ABApBpABA
BABAA
ABApBpABA
BABAAprq
pu
,
2cosh222sinh2sin
2cosh2sinh4
2
3
2cosh222sinh2sin
2cosh2sinh4
2
32
8
2
22
222
22
2222
19
ABApBpABA
BABAA
ABApBpABA
BABAAprq
pu
109
where RBA 0, are constants and gratify the condition .022 BA
,coshsinh2
sec2
2
3
coshsinh2
sec2
2
32
8
2222
20
p
h
p
hprq
pu
Fig. 4.2. Solution 20u explains the soliton solution for corresponding to the values
.2,1,3 rqp
,sinhcosh2
csc2
2
3
sinhcosh2
csc2
2
32
8
2222
21
p
h
p
hprq
pu
,22sinh22cosh
2sinh12sec4
2
3
22sinh22cosh
2sinh12sec4
2
32
8
2222
22
ip
ih
ip
ihprq
pu
,22cosh22sinh
2cosh12csc4
2
3
22cosh22sinh
2cosh12csc4
2
32
8
2222
23
p
h
p
hprq
pu
.sinhcosh2
2csc2
2
3
sinhcosh2
2csc2
2
32
8
2222
24
p
h
p
hprq
pu
Family 3. When 0r and ,0qp the solutions are
,sinhcosh
sinhcosh
2
3
sinhcosh
sinhcosh
2
32
8
22
25
pppd
ppp
pppd
pppprq
pu
,
sinhcosh2
3
sinhcosh2
32
8
22
26
pppd
dp
pppd
dpprq
pu
where d is an arbitrary constant.
110
Fig. 4.3. Illustrates the form of the kink-type solution of 26u for .0,2,2 rqp Kink
waves are traveling waves which take place from one asymptotic state to another. The
Family 4. When 0q and ,0 pr the solution is
,2
3
2
32
8
2
11
2
27
dq
q
dq
qprq
pu
where 1d is an arbitrary constant.
Fig. 4.4. Explains the shape of the soliton solution 27u corresponding to the parameter
values .0,3,0 rqp
111
Example 4.2.2. The Sixth-Order Boussinesq Equation
Consider the sixth-order Boussinesq equation [198]
.09045)(153015 62
222
234 xxxxxxxxxtt uuuuuuuuuuuu (4.10)
The wave variable (1.30) converts (4.10) in an ordinary differential equation as follows:
,09045513015 622242 uuuuuuuuuuuuV (4.11)
where 4u and 6u denotes the fourth order and sixth order derivatives of u with respect
to . Integrating (4.11) once with respect to yields:
,01515451 )5(22 uuuuuuVuC (4.12)
where C is a constant of integration. Now, considering the homogeneous balance
between the highest order derivative and nonlinear term in (4.12), we obtain .2n
According to step 3 of section 1.4.4, the trial solution of (4.12) becomes:
,)(2
210
G
Ga
G
Gaau (4.13)
where ia are constants to be indomitable and G is the solution of the generalized Riccati
equation (4.5). Using (4.5), equation (4.13) can be rewritten as:
.)()()( 212
110 GqGrpaGqGrpaau (4.14)
Proceeding as before, the following solution set is attained:
.0,1168,2,2,3
4
3
1 222421
20 CrqrqppVaparqpa (4.15)
Substituting (4.15) into (4.13), the following solution is obtained:
,223
4
3
1)(
2
2
G
G
G
Gprqpu (4.16)
112
where .1168 2224 trqqrppx
Now on the basis of the solutions of (4.5), the families of exact solutions are:
Family 1. When 042 qrp and ),0or (0 qrqp the solutions are:
,tan2
sec22
tan2
sec22
3
4
3
12
22222
1
ppprqpu
where ,1168,42
1 22242 trqqrppxpqr and rqp ,, are arbitrary
constants.
,cot2
csc22
cot2
csc22
3
4
3
12
22222
2
ppprqpu
,22sin22cos
2sin12sec42
22sin22cos
2sin12sec42
3
4
3
12
222
3
ppprqpu
,22cos22sin
2cos12csc42
22cos22sin
2cos12csc42
3
4
3
12
222
4
ppprqpu
,2cos2sin
csc22
2cos2sin
csc22
3
4
3
1222
25
ppprqpu
,
3
4
3
1
22cos22sin2sin22cos
2sin2sin2cos42
22cos22sin2sin22cos
2sin2sin2cos42
2
2
222222
222
222222
222
6
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
,
3
4
3
1
22cos22sin2sin22cos
2sin2sin2cos42
22cos22sin2sin22cos
2sin2sin2cos42
2
2
222222
222
222222
222
7
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
where RBA 0, are constants and gratify the condition 022 BA .
113
,4cossin4cos22
sin2cossec22
4cossin4cos22
sin2cossec22
3
4
3
1
2
222
2
222
22
8
prqp
p
prqp
pprqpu
,cossin4cos22
cos2sincsc22
cossin4cos22
cos2sincsc22
3
4
3
1
2
222
2
222
22
9
pprqp
p
pprqp
pprqpu
,2cos22sin122cos2
22sin22cos2sin12sec22
2cos22sin122cos2
22sin22cos2sin12sec22
3
4
3
1
2
22
2
22
22
10
prqp
p
prqp
pprqpu
,22sin22sin122cos2
22cos22sin2csc22
22sin22sin122cos2
22cos22sin2csc22
3
4
3
1
2
2
2
2
22
11
rqppprq
p
rqppprq
pprqpu
.cossin4cos22
cos2sincsc22
cossin4cos22
cos2sincsc22
3
4
3
1
2
222
2
222
22
12
pprqp
p
pprqp
pprqpu
Family 2. When 042 qrp and ),0or (0 qrqp the soliton-like solutions are:
,tanh2
sec22
tanh2
sec22
3
4
3
12
22222
13
p
h
p
hprqpu
where ,1168,42
1 22242 trqqrppxqrp and rqp ,, are arbitrary
constants.
114
Fig. 4.5. Solution 13u elucidates the soliton for .1,2,3 rqp The particular types
0)(),(),( uuu as , .tVx Solitons have a amazing property that
,coth2
csc22
coth2
csc22
3
4
3
12
22222
14
p
h
p
hprqpu
,22sinh22cosh
2sinh12sec42
22sinh22cosh
2sinh12sec42
3
4
3
1222
215
ip
ih
ip
ihprqpu
,22cosh22sinh
2cosh12csc42
22cosh22sinh
2cosh12csc42
3
4
3
12
222
16
p
h
p
hprqpu
,2/coth2/tanh12/cosh2
2/sec2
2/coth2/tanh12/cosh2
2/sec2
3
4
3
1
2
2
22
2
222
17
p
h
p
hprqpu
,
2cosh222sinh2sin
2cosh2sinh42
2cosh222sinh2sin
2cosh2sinh42
3
4
3
1
2
22
222
22
2222
18
ABApBpABA
BABAA
ABApBpABA
BABAAprqpu
115
,
2cosh222sinh2sin
2cosh2sinh42
2cosh222sinh2sin
2cosh2sinh42
3
4
3
1
2
22
222
22
2222
19
ABApBpABA
BABAA
ABApBpABA
BABAAprqpu
where RBA 0, are constants and gratify the condition .022 BA
,coshsinh2
sec22
coshsinh2
sec22
3
4
3
1222
220
p
h
p
hprqpu
,sinhcosh2
csc22
sinhcosh2
csc22
3
4
3
1222
221
p
h
p
hprqpu
,22sinh22cosh
2sinh12sec42
22sinh22cosh
2sinh12sec42
3
4
3
1222
222
ip
ih
ip
ihprqpu
,22cosh22sinh
2cosh12csc42
22cosh22sinh
2cosh12csc42
3
4
3
1222
223
p
h
p
hprqpu
.sinhcosh2
2csc22
sinhcosh2
2csc22
3
4
3
12
222
24
p
h
p
hprqpu
Family 3. When 0r and ,0qp the solutions are:
,sinhcosh
sinhcosh2
sinhcosh
sinhcosh2
3
4
3
12
225
pppd
ppp
pppd
pppprqpu
,
sinhcosh2
sinhcosh2
3
4
3
12
226
pppd
dp
pppd
dpprqpu
where d is an arbitrary constant.
Family 4. When 0q and ,0 pr the solution is:
,223
4
3
12
11
227
dq
q
dq
qprqpu
where 1d is an arbitrary constant.
116
Fig. 4.6. Demonstrates the singular soliton solution 27u for .0,1,0 rqp
Example 4.2.3. The Fifth Order CDGSK Equation
Consider the following fifth order CDGSK equation [43] in the form
.05 2 xxxxxxxxxxxxt uuuuuuuu (4.17)
The fifth order CDGSK equation (4.17) is a completely integrable. The first four
conserved densities of equation (4.17) are:
.4
3
4
9
4
1
,3
1
,
,
22
244
233
2
1
xx
x
uuuuT
uuT
T
uT
(4.17a)
Now, using the traveling wave variable tVxutxu ),(),( that converts (4.17)
into an ODE as follows:
,05 25 uuuuuuuuV (4.18)
where 5u indicates the ordinary derivative of u with respect to . Integrating (4.18)
once with respect to yields:
117
,03
55 34 uuuuuVC (4.19)
where C is a constant of integration. Considering the homogeneous balance between
4u and 3u in (4.19), we deduced that .2n
According to step 3 of section 1.4.4, the trial solution of (4.19) takes the form
.)(2
210
G
Ga
G
Gaau (4.20)
Using (4.5), equation (4.20) can be rewritten as:
.)()()( 212
110 GqGrpaGqGrpaau (4.21)
Proceeding as before, the solution of the obtained system is
.3
2
3
128832
,168,6,6,4
6334222
222421
20
prqqrprqpC
rqrqppVaparqpa
(4.22)
Substituting (4.22) into (4.20), the following solution is obtained:
,/6/64)(22 GGGGprqpu (4.23)
where .168 2224 trqrqppx
Now on the basis of the solutions of (4.5), the families of exact solutions are:
Family 1. When 042 qrp and ),0or (0 qrqp the periodic form solutions are
,tan2
sec26
tan2
sec264
22222
21
ppprqpu
where ;168,42
1 22242 trqqrppxpqr rqp ,, are arbitrary constants.
118
Fig. 4.7. Solution 1u explains the soliton for .1,1,1 rqp The particular types of
solitary waves are solitons. The soliton solution is a spatially confined solution, hence, 0)(),(),( uuu as , .tVx An amazing chattel of solitons is that it
maintains its individuality upon interacting with other solitons.
,cot2
csc26
cot2
csc264
22222
22
ppprqpu
,22sin22cos
2sin12sec46
22sin22cos
2sin12sec464
222
23
ppprqpu
,22cos22sin
2cos12csc46
22cos22sin
2cos12csc464
222
24
ppprqpu
,2cos2sin
csc26
2cos2sin
csc264
2222
5
ppprqpu
,4
22cos22sin2sin22cos
2sin2sin2cos46
22cos22sin2sin22cos
2sin2sin2cos46
2
2
222222
222
222222
222
6
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
119
,4
22cos22sin2sin22cos
2sin2sin2cos46
22cos22sin2sin22cos
2sin2sin2cos46
2
2
222222
222
222222
222
7
rqp
BApBApAABBAA
BAABBAA
BApBApAABBAA
BAABBAApu
where RBA 0, are constants and gratify the condition 022 BA .
,4cossin4cos22
sin2cossec26
4cossin4cos22
sin2cossec264
2
222
2
222
22
8
prqp
p
prqp
pprqpu
,cossin4cos22
cos2sincsc26
cossin4cos22
cos2sincsc264
2
222
2
222
22
9
pprqp
p
pprqp
pprqpu
,2cos22sin122cos2
22sin22cos2sin12sec26
2cos22sin122cos2
22sin22cos2sin12sec264
2
22
2
22
22
10
prqp
p
prqp
pprqpu
,22sin22sin122cos2
22cos22sin2csc26
22sin22sin122cos2
22cos22sin2csc264
2
2
2
2
22
11
rqppprq
p
rqppprq
pprqpu
,cossin4cos22
cos2sincsc26
cossin4cos22
cos2sincsc264
2
222
2
222
22
12
pprqp
p
pprqp
pprqpu
Family 2. When 042 qrp and ),0or (0 qrqp the solutions are:
,tanh2
sec2
2
3
tanh2
sec264
22222
213
p
h
p
hprqpu
120
where ,168,42
1 22242 trqqrppxqrp qp, and r are arbitrary
constants.
Fig. 4.8. Solution 13u elucidates the soliton for .5.0,1,2 rqp The particular types of
solitary waves are solitons. The soliton solution is a spatially confined solution, hence, 0)(),(),( uuu as , .tVx Solitons have an amazing property that
it keeps its characteristics upon interacting with other solitons.
,coth2
csc26
coth2
csc264
22222
214
p
h
p
hprqpu
Fig. 4.9. Illustrates the singular soliton solution of 14u for .1,2,3 rqp
121
,22sinh22cosh
2sinh12sec46
22sinh22cosh
2sinh12sec464
2222
15
ip
ih
ip
ihprqpu
,22cosh22sinh
2cosh12csc46
22cosh22sinh
2cosh12csc464
2222
16
p
h
p
hprqpu
,2/coth2/tanh12/cosh2
2/sec6
2/coth2/tanh12/cosh2
2/sec64
2
2
22
2
222
17
p
h
p
hprqpu
,
2cosh222sinh2sin
2cosh2sinh46
2cosh222sinh2sin
2cosh2sinh464
2
22
222
22
2222
18
ABApBpABA
BABAA
ABApBpABA
BABAAprqpu
,
2cosh222sinh2sin
2cosh2sinh46
2cosh222sinh2sin
2cosh2sinh464
2
22
222
22
2222
19
ABApBpABA
BABAA
ABApBpABA
BABAAprqpu
where RBA 0, are constants and gratify the condition .022 BA
,coshsinh2
sec26
coshsinh2
sec264
222
220
p
h
p
hprqpu
,sinhcosh2
csc26
sinhcosh2
csc264
2222
21
p
h
p
hprqpu
,22sinh22cosh
2sinh12sec46
22sinh22cosh
2sinh12sec464
2222
22
ip
ih
ip
ihprqpu
,22cosh22sinh
2cosh12csc46
22cosh22sinh
2cosh12csc464
222
223
p
h
p
hprqpu
,sinhcosh2
2csc26
sinhcosh2
2csc264
222
224
p
h
p
hprqpu
122
Family 3. When 0r and ,0qp the solutions are
,sinhcosh
sinhcosh6
sinhcosh
sinhcosh64
2
225
pppd
ppp
pppd
pppprqpu
,
sinhcosh6
sinhcosh64
2
226
pppd
dp
pppd
dpprqpu
where d is an arbitrary constant.
Family 4. When 0q and ,0 pr the solution is
,664
2
11
227
dq
q
dq
qprqpu
where 1d is an arbitrary constant.
Fig. 4.10. Shows the shape of the soliton solution 27u for .0,2,0 rqp
Example 4.2.4. The (3 + 1)-Dimensional Modified KdV-ZK Equation
Consider the (3+1)-dimensional modified KdV-ZK equation [232] in the form
,02 zzxyyxxxxxt uuuuuu (4.24)
where is a nonzero constant parameter.
Now, using the wave transformation tVzyxutzyxu ),(),,,( that converts
(4.24) in an ODE as follows
123
,032 uuuuV (4.25)
Integrating (4.25) once with respect yields
,033
1 3 uuVuC (4.26)
where C is an integral constant which is to be determined later. Now, cconsidering the
homogeneous balance between u and 3u in (4.26), we deduced that .1n
According to step 3 of section 1.4.4, the trial solution of (4.26) takes the form:
./)( 10 GGaau (4.27)
Using (4.5), equation (4.27) can be rewritten as:
).()( 110 GqGrpaau (4.28)
Proceeding in a similar manner as before yields:
,2
36,12
2
3,
2
6,
2
3 210
pqriCrqpV
iip (4.29)
Family 1. When 042 qrp and ),0or (0 qrqp the solutions are:
,tan2
sec2
2
6
2
3 22
1
p
iipu
Fig.4.11. Solution 1u represents the exact periodic traveling wave solution for
.9,2,1,1 rqp The traveling wave solutions which are periodic in nature like
)cos( tx are called periodic solutions.
124
where ;122
3,4
2
1 22 trqpzyxpqr
qp, and r are arbitrary constants.
,cot2
csc2
2
6
2
3 22
2
p
iipu
,22sin22cos
2sin12sec4
2
6
2
3 2
3
p
iipu
,22cos22sin
2cos12csc4
2
6
2
3 2
4
p
iipu
,2cos2sin
csc2
2
6
2
3 2
5
p
iipu
,
2
3
22cos22sin2sin22cos
2sin2sin2cos4
2
6
222222
222
6
ip
BApBApAABBAA
BAABBAAiu
,
2
3
22cos22sin2sin22cos
2sin2sin2cos4
2
6
222222
222
7
ip
BApBApAABBAA
BAABBAAiu
where RBA 0, are constants and gratify the condition .022 BA
,4cossin4cos22
sin2cossec2
2
6
2
3222
2
8
prqp
piipu
,cossin4cos22
cos2sincsc2
2
6
2
3222
2
9
pprqp
piipu
,2cos22sin122cos2
22sin22cos2sin12sec2
2
6
2
322
2
10
prqp
piipu
,22sin22sin122cos2
22cos22sin2csc2
2
6
2
32
2
11
rqppprq
piipu
,cossin4cos22
cos2sincsc2
2
6
2
3222
2
12
pprqp
piipu
125
Family 2. When 042 qrp and ),0or (0 qrqp the solutions are
,tanh2
sec2
2
6
2
3 22
13
p
hiipu
where ;122
3,4
2
1 22 trqpzyxqrp
qp, and r are arbitrary constants.
Fig. 4.12. Solution 13u explains the soliton for .4,1,3,4 rqp The particular
types of solitary waves are solitons. The soliton solution is a spatially confined solution, hence 0)(),(),( uuu as , .tVx An amazing chattel of solitons is
that it maintains its individuality upon interacting with other solitons.
,coth2
csc2
2
6
2
3 22
14
p
hiipu
,22sinh22cosh
2sinh12sec4
2
6
2
3 2
15
ip
ihiipu
,22cosh22sinh
2cosh12csc4
2
6
2
3 2
16
p
hiipu
,2/coth2/tanh12/cosh2
2/sec
2
6
2
32
22
17
p
hiipu
126
,
2cosh222sinh2sin
2cosh2sinh4
2
6
2
322
222
18
ABApBpABA
BABAAiipu
,
2cosh222sinh2sin
2cosh2sinh4
2
6
2
322
222
19
ABApBpABA
BABAAiipu
where RBA 0, are constants and gratify the condition .022 BA
,coshsinh2
sec2
2
6
2
3 2
20
p
hiipu
,sinhcosh2
csc2
2
6
2
3 2
21
p
hiipu
,22sinh22cosh
2sinh12sec4
2
6
2
3 2
22
ip
ihiipu
,22cosh22sinh
2cosh12csc4
2
6
2
3 2
23
p
hiipu
,sinhcosh2
2csc2
2
6
2
3 2
24
p
hiipu
Family 3. When 0r and ,0qp the solutions are:
,sinhcosh
sinhcosh
2
6
2
325
pppd
pppiipu
,
sinhcosh2
6
2
326
pppd
dpiipu
where d is an arbitrary constant.
Family 4. When 0q and ,0 pr the solution is:
,2
6
2
3
1
27
dq
qiipu
where 1d is an arbitrary constant.
127
Discussion
In this chapter, by using the alternative )/( GG -expansion method, copious traveling
wave solutions of diverse nonlinear evolution equations have been attained in a consistent
way, in which the generalized Riccati equation is used as an auxiliary equation. The
attained solutions are noteworthy for the elucidation of some realistic physical
phenomena. It is revealed that the alternative )/( GG -expansion method together with
the generalized Riccati equation offers a sophisticated mathematical tool for solving
nonlinear partial differential equations. The graphical depictions together with the
numerical results divulge the complete fidelity and lofty effectiveness of the algorithm.
128
Chapter 5
Traveling Wave Solutions of Nonlinear Partial Differential
Equations by )/1,/( GGG -Expansion Method
129
5.1. Introduction
It has recently become more important to obtain exact solutions of nonlinear partial
differential equations through symbolic computer algebra that facilitates complex and
dreary algebraic computations. Calculating the exact numerical solutions, particularly,
traveling wave solutions of nonlinear differential equations in mathematics and
mathematical physics plays an important role in soliton theory [45, 222]. Mathematical
modeling of physical systems is normally explained with nonlinear differential equations.
These equations are mathematical models of complex physical phenomena that arise in
engineering and mechanics. Various effective methods have been developed to recognize
the mechanism of these physical models, which help the engineers and physicists to a
great extent by helping them to ensure that they have the adequate knowledge to solve the
physical problems. In the past decades, there has been significant progress in the
development of constructive methods for obtaining exact solutions of NLEEs. These
methods are; Modified Simple Equation [107, 264], First Integration [206] and Variation
of Parameter [171, 172] methods.
In 2010, Li et al. [116] developed a relatively new technique )1,/( GGG -expansion
method to find the traveling wave solutions of the Zakharov equations. It is worth
mentioning that recently Zayed and Abdelaziz [267] applied )1,/( GGG -expansion
method for finding traveling wave solutions of the nonlinear (3 + 1)-dimensional
Kadomtsev-Petviashvili equation. Zayed et al. [261] also applied this technique to solve
nonlinear KdV-mKdV equation. The basic idea of )1,/( GGG -expansion method is that
traveling wave solutions of nonlinear evolution equations can be expressed by a
polynomial in two variables )/( GG and )/1( G in which )(GG satisfies a second
order linear ordinary differential equation as an auxiliary equation,
,)()( GG
and sets GG /)( and ,/1)( G then
,2 .
This chapter comprises the applications of )1,/( GGG -expansion method for traveling
wave solutions of nonlinear partial differential equations [30, 188, 200]. The proposed
130
technique provides useful and new traveling wave solutions of the nonlinear PDEs, which
differ from the solutions, obtained by using the other existing techniques.
5.2. Numerical Examples
In this section some examples are given to elaborate the effectiveness of the well known
direct computational method called )/1,/( GGG -expansion method. The graphical
representations together with the numerical results disclose the complete trustworthiness
and high efficiency of the method.
Example 5.2.1. The Positive Gardner-KP Equation
Consider the positive Gardner-KP equation [200] as follows,
.066 2 yyxxxxxxt uuuuuuu (5.1)
Bin and Qiang [38] derived the conservation laws for the positive Gardner-KP equation
(5.1) by using the adjoint equation and symmetries.
Using the wave transformation tVyxPP ),( into (5.1) and integrating once
and setting the constant of integration to zero yields:
.0661 2 uuuuuuV (5.2)
According to step 3 of section 1.4.5, the solution of (5.2) is can be articulated by a power
series in and as follows
M
n
nn
M
n
nn bau
1
1
0
, (5.3)
where Mnan ,,3,2,1 and Mnbn ,,3,2,1 are constants to be determine later
and , are given by,
,)(
G
G
,
1)(
G (5.4)
where the following equation
,0 GG (5.5)
131
is used as an auxiliary equation.
The general solutions of (5.5) are followed by Li [116].
Applying the balancing principle betweenu and uu 2 in (5.2), we deduced that 1M .
Therefore, the trail solution becomes,
,110 baau (5.6)
where ,0a 1a and 1 b are constants which are to be determined later. Here three cases are
to be discussed as follows:
Case 1. When 0 (Hyperbolic function solutions).
If ,0 inserting (5.6) along with (1.40) and (1.41) into (5.2), the left-hand side of (5.2)
becomes a polynomial in and . Setting each coefficient of this polynomial to zero
yields a system of algebraic equations in ,0a ,,, , 11 ba V and as follows:
,06618
: 13122
2114
aa
ba
,0612
121261212: 2
1210222
231
22
210
22
1
22
121
22
2103
aaa
bbabbaba
,068
6612612324
:
11101
311
20222
22211
22
11
22
110
22
21
22
22112
Vaaaaa
aaabababaaaba
,0612
12612612: 2
1210222
331
22
221
22
21
21
22
21
22
22101
aaa
bbbabba
,06186
: 112122
313
bbab
(5.7)
,066651212
24126122424:
,0126122442
:
1110211
2011
21
210
222
2231
22
21
22
231
22
21
22
210
22
21
21
1131111022
2112
Vbbbaababbaaa
bbbbbaba
baaabaaba
,066512
6241261824
:
1110111110
120222
32211
22
211
22
31
22
2211
22
21101
Vaaaabaabaa
aababaababaa
132
.06
261261263
:
1110
211
20222
23211
22
211
22
2110
22
3211
22
2210
Vaaaa
aaabababaabaa
Solving the above system of equations (5.7), following two solution sets are obtained:
Set 1.
.,)(2
)2
,)(
,0,12
1
22
22
2223
22
1122
0
BAV
baa
(5.8)
Now, the traveling wave solution of (5.1) becomes:
,coshsinh
)(1
2
1,,
22
221
BAtyxu
where .)(2
)222
2223
tyx
In particular, if setting 0 and 0,0 BA in 1u , the solitary wave solution is
Fig. 5.1. Solution 11u explains the soliton solution for .,1 xy Solitons are particular
kinds of solitary waves. An amazing chattel of solitons is that it maintains its individuality upon interacting with other solitons.
133
and if setting 0 and 0,0 BA in 1u , the following solitary wave solution is,
.csc2
1,,2
1 htyxu
Fig. 5.2. Solution 21u explains the soliton solution for .,1 xy
Set 2.
.,2
1,
4,
2
1,
2
1 2222
110 BAVbiaa
(5.9)
Now, the traveling wave solution of (5.1) becomes:
,coshsinh4
coshsinh
sinhcosh
2
1
2
1,,
22
2/3
2
BA
BA
BAityxu
where .2
1tyx
In particular, by setting 0 and 0,0 BA in 2u , the following solitary solution is
obtained,
,sec2
1tanh
2
1
2
1,,1
2 hityxu
134
Fig. 5.3. Solution 12u explains the soliton solution for .,1 xy
while, if setting 0 and 0,0 BA in 2u , the following solitary solution is,
.csccoth2
1
2
1,,2
2 htyxu
Case 2. When 0 (Trigonometric function solutions).
If ,0 substituting (5.6) along with (1.40) and (1.42) into (5.2), the left- hand side of
(5.2) becomes a polynomial in . and Setting each coefficient of this polynomial to
zero yields a system of algebraic equations in ,0a ,,, , 11 ba V and as follows:
,06618
: 13122
2114
aa
ba
,0612
12661212: 2
1210222
231
22
21
22
1
22
210
22
1213
aaa
bbbbaba
,068
6612123246
:
11101
311
20222
22211
22
110
22
21
22
2211
22
112
Vaaaaa
aaababaaababa
,0612
12661212:
21
210
222
331
22
221
22
21
22
2210
22
21
211
aaa
bbbbaba
,06186
: 112122
313
bbab
(5.10)
135
,066651212
24126122424:
,0126122442
:
1110211
2011
21
210
222
2231
22
21
22
231
22
21
22
21
21
22
210
1131111022
2112
Vbbbaababbaaa
bbbbbaba
baaabaaba
,066512
6241218246
:
1110111110
120222
32211
22
211
22
2211
22
2110
22
311
Vaaaabaabaa
aababababaaa
.06
261266312
:
1110
211
20222
23211
22
211
22
3211
22
221
22
21100
Vaaaa
aaabababaabaa
Solving the above system of algebraic equations, following two solution sets are
obtained:
Set 3.
.,2
)2
,,0,12
1
22
22
2223
22
1122
0
BAV
baa
(5.11)
Now, the traveling wave solution of (5.1) becomes
,cossin
12
1,,
22
223
BAtyxu
where .
2
222
2223
tyx
In particular, if setting 0 and 0,0 BA in 3u , the solitary wave solution is,
,csc2
1,,1
3 ityxu
while, if setting 0 and 0,0 BA in 3u , the following solitary wave solution is,
.sec2
1,,2
3 ityxu
136
Fig. 5.4. Solution 23u shows the soliton solution for .,2 xy Solitons are particular
kinds of solitary waves. Solitons have a notable property that it keeps its uniqueness upon
Set 4.
.,2
1,
4,
2
1,
2
1 2222
110 BAVbiaa
(5.12)
,cossin4
cossin
sincos
2
1
2
1,,
22
2/3
4
BA
BA
BAityxu
where .2
1tyx
In particular, by setting 0 and 0,0 BA in 4u , the solitary wave solution is,
,sectan2
1
2
1,,1
4 ityxu
while, if setting 0 and 0,0 BA in 4u , the solitary wave solution is,
.csccot2
1
2
1,,2
4 ityxu
137
Fig. 5.5. Solution 24u shows the soliton solution for .,2 xy Solitons are particular
kinds of solitary waves. Solitons have a notable property that it keeps its uniqueness upon interacting with other solitons.
Case 3. When 0 (Rational function solutions).
If ,0 inserting (5.6) along with (1.40) and (1.43) into (5.2), the left-hand side of (5.2)
becomes a polynomial in . and Setting each coefficient of the resulted polynomial to
zero yields a system of algebraic equations in ,0a , , 11 ba andV as follows:
,0662
18: 1
312
2114
aa
BA
ba
,0612
2
12
2
12
2
12
2
6
2
6: 2
121022
31
2
121
2
210
2
21
2
13
aaaBA
b
BA
ba
BA
ba
BA
b
BA
b
,066
2
12
2
6
2
3
2
12: 11101
2022
2211
2
11
2
21
2
1102
VaaaaaaBA
ba
BA
ba
BA
a
BA
baa
,012612242
42:
,06182
6:
113111102
2112
11212
313
baaabaaBA
ba
bbaBA
b
(5.13)
,066612
2
24
2
24
2
12
2
12
2
24:
1110211
20
210
22
231
2
21
21
2
21
2
21
2
210
Vbbbaabaaa
BA
b
BA
ba
BA
b
BA
b
BA
ba
138
.06
62
24
2
12
2
24
2
6:
1110
12022
3211
2
211
2
2110
2
311
Vaaaa
aaBA
ba
BA
ba
BA
baa
BA
a
Solving the system (5.13), the following two solution sets are obtained:
Set 5.
.
22
32,2,0,
21
2
12
222
112
0BA
BAVBAba
BAa
(5.14)
Now, the traveling wave solution of (5.1) becomes:
,2
12
21
2
1,,
2
2
205
BABA
BAatyxu
where .
22
322
22
tBA
BAyx
Set 6.
.2
1,2
2
1,
2
1,
2
1 2110 VBAbiaa (5.15)
,2
12
2
1
22
1
2
1,,
2
2
26
BABA
BA
Aityxu
where .2
1tyx
Example 5.2.2. The (2 + 1)-Dimensional CBS Equation
Now, consider the (2 + 1)-dimensional CBS equation [188] in the form
.024 zxxzxxzxxxtx uuuuuu (5.16)
This equation is used to describe the interaction of a Riemann wave promulgating along
the z-axis with a long wave along the x-axis.
Using the traveling wave transformation ,),(),,( tVwzkxutzxu that converts
(5.16) into an ordinary differential equation
139
.06 2)4(3 uuwkuwkukV (5.17)
Integrating (5.17) with respect to and setting the constant of integration to zero yields:
,0)(3 223 uwkuwkukV (5.18)
where primes denote the derivatives with respect to . Applying the homogeneous
balancing principle between u and 2)(u , we deduced that 1M . According to step 3 of
section 1.4.5, the solution of (5.18) can be expressed by a finite power series in and
as follows:
,110 baau (5.19)
where ,0a 1a and 1 b are constants to be determined later. The following cases are to be
discussed as follows:
Case 1. Hyperbolic function solutions .0
If ,0 inserting (5.19) along with (1.40) and (1.41) into (5.18), the left-hand side of
(5.18) becomes a polynomial in . and Setting each coefficient of this polynomial to
zero yields a system of algebraic equations in ,0a ,,, , 11 ba V and as follows:
,0333
86:
,066
:
,03
63:
22
221
2
22
21
3
22
221
2
132
12
12
221
3
2211
23
22
21
2
132
124
wbkwakwakwakawkVka
wbkbwak
wbkwakwak
,066
:22
21
3
22
211
21
wbkbwak (5.20)
,06
612:
,066:
22
21
221
21
32
13
1123
wbkawkwak
wbkbwak
140
.066
56:
,033
23:
22
31
3
22
321
2
132
12
10
22
221
3
22
2221
22
1322
12
11
wakwakwakawkVka
wakwakwakwakVka
Solving the above system of algebraic equations, the following solution set is obtained:
.,,,, 22222
1100 BAwkVkbkaaa
(5.21)
Now, the traveling wave solution of (5.16) becomes:
,coshsinh
coshsinh
sinhcosh,,
222/3
01
BA
k
BA
BAkatzxu
where .2 twkwzkx
In particular, by taking 0 and 0,0 BA in 1u , the solution is,
,sectanh,, 011 hikatzxu
Fig. 5.6. Shows the form of the exact kink-type solution of 11u for ,0,1 0
.0,1 zk Kink waves are traveling waves which take place from one asymptotic state
to another. The kink solution comes close to a constant at infinity.
and if taking 0 and 0,0 BA in 1u , the solitary wave solution is,
.csccoth,, 021 hkatzxu
141
Fig. 5.7. Shows the form of the singular kink solution of 21u for .0,1,0,1 0 zk
Case 2. If ,0 substituting (5.19) along with (1.40) and (1.42) into (5.18), the equation
(5.18) becomes a polynomial and setting each coefficient to zero yields a system of
equations in unknowns and after solving, the following solution is obtained:
.,,,, 22222
1100 BAwkVkbkaaa
(5.22)
Now, the traveling wave solution of (5.16) becomes:
,cossin
cossin
sincos,,
222/3
02
BA
k
BA
BAkatzxu
where .2 twkwzkx
In particular, if setting 0 and 0,0 BA in 2u , the solitary solution is,
,sectan,, 012 katzxu
142
Fig.5.8. Solution 12u represents the exact periodic traveling wave solution for
,0,1 0 .1,,1 wxzk The traveling wave solutions which are periodic in
nature like )cos( tx are called periodic solutions.
Similarly, taking 0 and 0,0 BA in 2u , the solitary wave solution is,
.csccot,, 022 katzxu
Example 5.2.3. The Modified Benjamin-Bona-Mahony Equation
Now, consider the nonlinear MBBM equation [30] in the form
,02 txxxxt uuuuu (5.23)
which was first derived to depict an ballpark figure for surface long waves in nonlinear
dispersive media. This equation can also characterize the hydro magnetic waves in cold
plasma and acoustic-gravity waves in compressible fluids [154].
The wave variable (1.35) converts (5.23) into an ODE as follows
,01 2 uVuuuV (5.24)
Applying the homogeneous balancing principle between u and ,2uu we deduced
that 1M . According to step 3 of section 1.4.5, the solution of (5.24) can be expressed
by a finite power series in and as
,110 baau (5.25)
where ,0a 1a and 1 b are constants to be determined later. Now, the three cases are as
follows:
143
Case 1. Hyperbolic function solutions .0
If ,0 substituting (5.25) along with (1.40) and (1.41) into (5.24), the left-hand side of
(5.24) becomes a polynomial and setting each coefficient to zero yields a system of
equations in ,0a ,,, , 11 ba V and as follows:
,0226
122:
,03
6:
121
210122222
2312
103
22
211
131
4
babaVbb
aa
baVaa
,0262
122:
,08
2234
1:
21
21
21
221022222
2312
101
11120
311
222
21
221
1102
1122
122
2
baVbbab
aa
VaVaaaaa
abbaaVaab
,07
412:
,036:
22
211
110131
2
22
31
1211
3
babaaVaa
bbaVb
(5.26)
02312
12:
,04
5221
44121
:
21
2110
2
22222
23211
120
1
222
2231
1121
2101
201
12
1023
12
121
2122
abbaVba
aaV
bbVbaaababV
bbabbaVb
.04
251
6431
:
222
32211
110120
31
2110
221122
0
babaaaaVV
Vabaaba
Solving the above system, we obtain the following two solution sets:
144
Set 1.
.,2)1()2(
3,
2)1()2(
)(2
),(2)1()2(
12,0
22
22022
22
22
3211
BAaV
ba
(5.27)
Now the traveling wave solution of (5.23) becomes:
,coshsinh
)(2)1()2(
12
2)1()2(
3, 22
32221
BA
txu
where .2)1()2(
)(222
22
tx
In particular, if taking 0 and 0,0 BA in 1u , the solitary wave solution is,
,sec1
6,1
1
htxu
Fig. 5.9. Solution 11u explains the soliton for .1 The particular types of solitary
waves are solitons. The soliton solution is a spatially confined solution, hence 0)(),(),( uuu as , .tVx An amazing chattel of solitons is that it
maintains its individuality upon interacting with other solitons.
145
while, if setting 0 and 0,0 BA in 1u , the solitary wave solution is,
.csc1
6,2
1
htxu
Set 2.
.,2
2,
)2(
)(3,
2
3,0 22
22
110 BAVbaa
(5.28)
Now in this result the traveling wave solution of (5.23) becomes:
,coshsinh
)2(
)(3
coshsinh
sinhcosh
2
3,
222/3
2
BA
BA
BAtxu
where .2
2tx
In particular, by setting 0 and 0,0 BA in 2u , the solution is,
,sec2
3tanh
2
3,1
2
htxu
Fig. 5.10. Shows the form of the exact kink-type solution of 12u for .1 Kink waves
are traveling waves which take place from one asymptotic state to another. The kink solution comes close to a constant at infinity.
146
while, if setting 0 and 0,0 BA in 2u , the solitary solution is,
.csccoth2
3,2
2
htxu
Case 2. If ,0 substituting (5.25) along with (1.40) and (1.42) into (5.24), the left-
hand side of (5.24) becomes a polynomial and setting each coefficient to zero yields a
system of equations in unknowns and after solving the system, two solutions are
obtained:
Set 3.
.,2)1()2(
)(2,
2)1()2(
3
),(2)1()2(
12,0
22
22
22
220
22
3211
BAVa
ba
(5.29)
Now, the traveling wave solution of (5.23) becomes:
,cossin
)(2)1()2(
12
2)1()2(
3, 22
32223
BA
txu
where .2)1()2(
)(222
22
tx
In particular, by taking 0 and 0,0 BA in 3u , the solitary solution is,
,csc1
6,1
3
txu
147
Fig. 5.11. Solution 13u explains the soliton for .1 Solitons are particular kinds of
solitary waves. An amazing chattel of solitons is that it maintains its individuality upon interacting with other solitons.
while, if setting 0 and 0,0 BA in 3u , the solitary solution is,
.sec1
6,2
3
txu
Fig.5.12. Solution 23u corresponds to the periodic traveling wave solution for .2
Set 4.
.,2
2,
)2(
)(3,
2
3,0 22
22
110 BAVbaa
(5.30)
Now, in this result the traveling wave solution of (5.23) becomes:
148
,cossin
)2(
)(3
cossin
sincos
2
3,
222/3
4
BA
BA
BAtxu
where .2
2tx
In particular, by setting 0 and 0,0 BA in 4u , the solitary solution is,
,sectan2
3,1
4
txu
Fig.5.13. Solution 14u corresponds to the periodic traveling wave solution for .1
while, if setting 0 and 0,0 BA in 4u , the solution is,
.csccot2
3,2
4
txu
Case 3. When ,0 by analogous computations, the following two solution sets are
obtained:
Set 5.
.342
)2(2
),2(342
12,0,
342
3
22
2
2
2211220
BA
BAV
BABA
baBA
a
(5.31)
149
Now, the traveling wave solution of (5.23) becomes:
,2
42
342
3,
2
2
225
BA
BA
BAtxu
where .342
)2(222
2
tBA
BAx
Set 6.
.1,2
)2(3,
2
3,0
2
110
VBA
baa
(5.32)
Now, the travelling wave solution of (5.23) becomes:
,2
2
2
3,
2
2
6
BA
BAAtxu
where .tx
Discussion
In this chapter )1,/( GGG -expansion method is applied to obtain new solitary wave
solutions of nonlinear evolution equations. The crucial advantage of )/1,/( GGG -
expansion method aligned with the fundamental )/( GG -expansion method is that it
offers abundant, new and general exact traveling wave solutions. These exact solutions
are of great significance in enlightening the internal mechanism of the complicated
physical phenomena. The closed-form of solutions assists the numerical researchers in
comparing the exactness of their outcomes and also helps them in the stability analysis.
150
Chapter 6
Applications of Novel )/( GG -Expansion Method to
Nonlinear Evolution Equations
151
6.1. Introduction
Currently, scientists believe that nonlinear science is the most important medium for the
fundamental understanding of nature. Many complex physical phenomena are often
described and modeled by nonlinear evolution equations. Therefore, the exact solutions
of the nonlinear evolution equations have become increasingly essential. These are not
only regarded as valuable tool in examining the accuracy of computational dynamics, but
also facilitate the researchers to readily understand the requisites of complex physical
phenomenon, for example, collision of two solitary solutions. The analytical solutions of
nonlinear evolutions are of crucial importance to help and to understand the internal
mechanism of the physical phenomena. In mathematics and physics, a soliton is a self-
reinforcing solitary wave, a wave packet that maintains its profile, while traveling at a
constant speed. In the past years, many powerful and direct methods have been developed
to discover special solutions, such as; Variational Iteration [173], Exp-Function [179],
Differential Transform [236] methods and others [235, 250].
Quite a lot of researchers carried out further research in order to ascertain the efficiency
and accuracy of )/( GG -expansion method and to enlarge the assortment of its
applicability. Alam et al. [26] introduced a novel )/( GG -expansion method for finding
the more general solutions of Boussinesq equation.
In this chapter the soliton solutions of nonlinear evolution equations [199, 216, 219, 231,
232] are obtained by applying the novel )/( GG -expansion method. This method offers
all types of solutions including; trigonometric function, hyperbolic function and rational
solutions. To illustrate the innovation, steadiness of the projected method, numbers of
nonlinear evolution equations are solved and abundant new families of exact solutions are
obtained.
6.2. Numerical Examples
In this section, a promising and powerful technique, called novel )/( GG -expansion
method is used to solve the equations [199, 216, 219, 231, 232], which arise in
mathematical physics, engineering sciences and applied mathematics. The accuracy of
the method verifies the efficiency and reliability of novel )/( GG -expansion method.
152
Example 6.2.1. The ZK-BBM Equation
Consider the ZK-BBM equation [199] in the form
.02 txxxxt buauuuu (6.1)
The ZK-BBM belongs to the integrable systems. Adem and Khalique [20] derived the
new conservation laws for the ZK-BBM equation by using Ibragimov conservation
theorem and the multiplier method.
Using the traveling wave variable (1.45) that converts (6.1) into an ODE and upon
integrating yields:
,01 12 CubVuauV (6.2)
where 1C is a constant of integration.
2m . Then according to step 2 of section 1.4.6, the trial solution of (6.2) becomes
.)()()()()(2
210
1
1
2
2
kkkku (6.3)
Using (6.3) in (6.2), the left hand side transforms into polynomials in iGGk )/(
and iGGk
)/( .,,2,1,0 Ni Equating all coefficients with the same power of
the resulted polynomials to zero, a set of algebraic equations (which are omitted here for
the sake of simplicity) for 0 , 1 , 2 , 1 , 2 , k , 1C andV is obtained. Solving the
indomitable set of algebraic equations, following three solution sets are obtained:
Set 1.
,
162
2a
CbV
,
2426 2
1a
kAACCkkCbV (6.4)
,0,0,,),
1882412121212(2
1
212
22220
kkVVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
,)1232
881616(4
1
2222
42222222222222221
VVCBVb
AVbBCAVbBAVbBVbCBVba
C
where k, V, A, B and C are arbitrary constants.
153
Set 2.
,18824121212122
1 222220 bVAVbVBbVBCbVCkbVkACbVkAbVkkbVC
a
,24332226 3222332
1 BCKCkACkkAAkkBAkCBka
bV
,2222226 24322342242
2 BCkABkCkACkkAAkkBBkkCa
bV
,VV ,kk ,02 ,01 (6.5)
,)1232
881616(4
1
2222
42222222222222221
VVCBVb
AVbBCAVbBAVbBVbCBVba
C
where k, V, A, B and C are arbitrary constants.
Set 3.
,
162
2a
CbV ,1882
2
1 20 VbVBCbVBbVA
a
,81632816)1(8
3 4222222
22 ABABCBBCACBCa
,VV ,)1(2
C
Ak ,01 ,01 (6.6)
,)12128128
51216256256(4
1
2222222
22242222222221
VVBAVbBCAVb
CBVbAVbBVbCBVba
C
where V, A, B and C are arbitrary constants.
Inserting equations (6.4)- (6.6) in (6.3), the following solutions of (6.1) are obtained:
.)/(16
)/(
2426)18
82412121212(2
1)(
22
22
22221
GGka
CbVGGk
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
(6.7)
154
.)/()22
2222(6
)/()2433
222(6
)2418
812121212(2
1)(
22
4322342242
13222
33222
2222
GGkBCkABk
CkACkkAAkkBBkkCa
bV
GGkBCkABCkACkkAAk
kBkkCa
bVbVCkbVAVbVB
bVBCbVkAbVkbVkACkbVCa
u
(6.8)
,)/()1(2
81632816)1(8
3
)/()1(2
161882
2
1)(
2
4222222
2
222
3
GGC
A
ABABCBBCACBCa
GGC
A
a
CbVVbVBCbVBbVA
au
(6.9)
where Vtx ; V, A, B and C are arbitrary constants.
Substituting the solutions )(G of (1.49) in (6.7) and simplifying, the following solutions
are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
116
)2/tanh(12
1
2426)18
82412121212(2
1)(
22
22
222211
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
155
Fig. 6.1. Shows the graph of cuspon of 11u for .1,1,3,1,2,1,1 VbakCBA
Unlike Peakons, where the derivative at the climax fluctuates only by a sign, the derivative at the hop of cuspons deviates.
,)2/coth(12
116
)2/coth(12
1
2426)18
82412121212(2
1)(
22
22
222221
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
Fig. 6.2. Exact singular soliton solution 21u for ,2,1,1 CBA .1,1,1,1 Vbak
156
,)(sec)tanh(12
116
)(sec)tanh(12
1
2426)18
82412121212(2
1)(
22
22
222231
hiAC
ka
CbV
hiAC
k
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
,)(csc)coth(12
116
)(csc)coth(12
1
2426)18
82412121212(2
1)(
22
22
222241
hAC
ka
CbV
hAC
k
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
,)4/coth()4/tanh(214
116
)4/coth()4/tanh(214
1
2426)18
82412121212(2
1)(
22
22
222251
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
,)sinh(
)cosh()(
12
116
)sinh(
)cosh()(
12
1
2426)18
82412121212(2
1)(
2222
22
22
222261
BF
FHFA
Ck
a
CbV
BF
FHFA
Ck
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
157
,)sinh(
)cosh()(
12
116
)sinh(
)cosh()(
12
1
2426)18
82412121212(2
1)(
2222
22
22
222271
BF
FHFA
Ck
a
CbV
BF
FHFA
Ck
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
where F and H are real constants.
,
)2/cosh()2/sinh(
)2/cosh(216
)2/cosh()2/sinh(
)2/cosh(2
2426)18
82412121212(2
1)(
22
22
222281
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAVbVB
bVBCbVCkbVkAbVkbVkACkbVCa
u
,
)2/sinh()2/cosh(
)2/sinh(216
)2/sinh()2/cosh(
)2/sinh(2
2426)1
882412121212(2
1)(
22
22
222291
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
158
Fig. 6.3. Solution 91u explains the soliton for ,2,1,1 CBA .1,1,3,1 Vbak
The particular types of solitary waves are solitons. The soliton solution is a spatially confined solution, hence 0)(),(),( uuu as , .tVx An amazing
chattel of solitons is that it maintains its individuality upon interacting with other solitons
,
)cosh()sinh(
)cosh(216
)cosh()sinh(
)cosh(2
2426)1
882412121212(2
1)(
22
22
2222101
iA
Bk
a
CbV
iA
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,
)sinh()cosh(
)sinh(216
)sinh()cosh(
)sinh(2
2426)1
882412121212(2
1)(
22
22
2222111
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
159
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(12
116
)2/tan(12
1
2426)1
882412121212(2
1)(
22
22
2222121
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
Fig.6.4. Solution 121u represents the exact periodic traveling wave solution for
,2,1,1 CBA .1,1,3,1 Vbak Periodic solutions are traveling wave
solutions that are periodic such as ).cos( tx
,)2/cot(12
116
)2/cot(12
1
2426)1
882412121212(2
1)(
22
22
2222131
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
160
Fig.6.5. Solution 131u represents the exact singular periodic traveling wave solutions for
2,1,1 CBA .1,1,3,2 Vbak
,)sec()tan(12
116
)sec()tan(12
1
2426)1
882412121212(2
1)(
22
22
2222141
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,)(csc)cot(12
116
)(csc)cot(12
1
2426)1
882412121212(2
1)(
22
22
2222151
hAC
ka
CbV
hAC
k
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
161
,)4/cot()4/tan(214
116
)4/cot()4/tan(214
1
2426)1
882412121212(2
1)(
22
22
2222161
AC
ka
CbV
AC
k
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,)sin(
)cos()(
12
116
)sin(
)cos()(
12
1
2426)1
882412121212(2
1)(
2222
22
22
2222171
BF
FHFA
Ck
a
CbV
BF
FHFA
Ck
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,)sin(
)cos()(
12
116
)sin(
)cos()(
12
1
2426)1
882412121212(2
1)(
2222
22
22
2222181
BF
FHFA
Ck
a
CbV
BF
FHFA
Ck
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
where F and H are real constants such that .022 HF
162
,
)2/cos()2/sin(
)2/cos(216
)2/cos()2/sin(
)2/cos(2
2426)1
882412121212(2
1)(
22
22
2222191
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,
)2/sin()2/cos(
)2/sin(216
)2/sin()2/cos(
)2/sin(2
2426)1
882412121212(2
1)(
22
22
2222201
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,
)cos()sin(
)cos(216
)cos()sin(
)cos(2
2426)1
882412121212(2
1)(
22
22
2222211
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
.
)2/sin()2/cos(
)2/sin(216
)2/sin()2/cos(
)2/sin(2
2426)1
882412121212(2
1)(
22
22
2222221
A
Bk
a
CbV
A
Bk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
163
When 0B and 0)1( CA , the solution is
,)sinh()cosh()1(
16
)sinh()cosh()1(
2426)1
882412121212(2
1)(
2
1
1
2
1
1
22
2222231
AAcC
Ack
a
CbV
AAcC
Ack
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
,)sinh()cosh()1(
))sinh()(cosh(16
)sinh()cosh()1(
))sinh()(cosh(
2426)1
882412121212(2
1)(
2
1
2
1
22
2222241
AAcC
AAAk
a
CbV
AAcC
AAAk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
where 1c is an arbitrary constant.
When 0 BA and 0)1( C , the solution of (6.1) is
,
)1(
116
)1(
12426)1
882412121212(2
1)(
2
2
2
2
22
2222251
cCk
a
CbV
cCk
a
kAACCkkCbVbVAV
bVBbVBCbVCkbVkAbVkbVkACkbVCa
u
where 2c is an arbitrary constant.
Inserting the solutions )(G of (1.49) in (6.8) and simplifying, the following solutions
are obtained
164
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(
12
1)2
22222(6
)2/tanh(12
1)243
3222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32
2233222
22212
AC
kBCk
ABkCkACkkAAkkBBkkCa
bV
AC
kBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
where Vtx ; k, A, B and C are arbitrary constants.
,)2/coth(
12
1)2
22222(6
)2/coth(12
1)243
3222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32
2233222
22222
AC
kBCk
ABkCkACkkAAkkBBkkCa
bV
AC
kBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
.))(sec)(tanh(
12
1)2
22222(6
))(sec)(tanh(12
1)243
3222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32
2233222
22232
hiAC
kBCk
ABkCkACkkAAkkBBkkCa
bV
hiAC
kBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
165
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(
12
1)2
22222(6
)2/tan(12
1)243
3222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32
2233222
222122
AC
kBCk
ABkCkACkkAAkkBBkkCa
bV
AC
kBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
,)2/cot(
12
1)2
22222(6
)2/cot(12
1)243
3222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32
2233222
222132
AC
kBCk
ABkCkACkkAAkkBBkkCa
bV
AC
kBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
.))sec()(tan(
12
1)2
22222(6
))sec()(tan(12
1)2
433222(6
)24
18812121212(2
1)(
2
2
4322342242
1
32223322
2222142
AC
kBCk
ABkCkACkkAAkkBBkkCa
bV
AC
kBCk
ABCkACkkAAkkBkkCa
bVbVCk
bVAVbVBbVBCbVkAbVkbVkACkbVCa
u
166
When 0 BA and 0)1( C , the solution of (6.1) is
,)1(
1)2
22222
(6
)1(
1)243
3222(6
)24
18812121212(2
1)(
2
2
2
43223422
42
1
3
32
2233222
222252
cCkBCk
ABkCkACkkAAkkBBk
kCa
bV
cCkBCkABCkACk
kAAkkBkkCa
bVbVCkbVAV
bVBbVBCbVkAbVkbVkACkbVCa
u
where 2c is an arbitrary constant.
Finally, substituting the solutions )(G of (1.49) in (6.9) and simplifying, the following
solutions are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1)81632
816()1(8
3))2/tanh((
)1(2
1
161882
2
1)(
2
4222
222
2
2
221
3
CABABCB
BCACBCaC
a
CbVVbVBCbVBbVA
au
where Vtx ; A, B and C are arbitrary constants.
,))2/coth(()1(2
1)81632
816()1(8
3))2/coth((
)1(2
1
161882
2
1)(
2
4222
222
2
2
222
3
CABABCB
BCACBCaC
a
CbVVbVBCbVBbVA
au
167
.)(sec)(tanh()1(2
1)81632
816()1(8
3)(sec)(tanh(
)1(2
1
161882
2
1)(
2
4222
222
2
2
223
3
hiC
ABABCB
BCACBCa
hiC
a
CbVVbVBCbVBbVA
au
For simplicity others families of exact solutions are omitted.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are,
,))2/tan(()1(2
1)81632
816()1(8
3))2/tan((
)1(2
1
161882
2
1)(
2
4222
222
2
2
2
2123
CABABCB
BCACBCaC
a
CbVVbVBCbVBbVA
au
Fig.6.6. Solution 123u represents the exact singular periodic traveling wave solution for
168
,))2/cot(()1(2
1)81632
816()1(8
3))2/cot((
)1(2
1
161882
2
1)(
2
4222
222
2
2
2
2133
CABABCB
BCACBCaC
a
CbVVbVBCbVBbVA
au
.)(sec)(tan()1(2
1)81632
816()1(8
3)(sec)(tan(
)1(2
1
161882
2
1)(
2
4222
222
2
2
2
2143
CABABCB
BCACBCaC
a
CbVVbVBCbVBbVA
au
When 0)1( C and 0 BA , the solution of (6.1) is
,)1(
1
)1(2)81632
816()1(8
3
)1(
1
)1(2
161882
2
1)(
2
2
4222
222
2
2
4
2225
3
cCC
AABABCB
BCACBCacCC
A
a
CbVVbVBCbVBbVA
au
where 2c is an arbitrary constant.
Example 6.2.2. The Symmetric Regularized Long Wave Equation
Consider the following SRLW equation [231] in the form
,0 xxtttxxtxxtt uuuuuuu (6.10)
which occurs in numerous physical applications including ion sound waves in plasma.
This equation is symmetrical with respect to x and t. It occurs in many nonlinear
problems of mathematical physics and applied mathematics.
Now, using the traveling wave variable ),(uu Vtx in (6.10) and integrating
twice yields:
,02
11 1
222 CuVuVuV (6.11)
169
where 1C is an integration constant. Now considering the homogeneous balance between
u and 2u in (6.11), we obtain .2m Then according to step 2 of section 1.4.6, the trial
solution of (6.11) becomes
.)()()()()(2
210
1
1
2
2
kkkku (6.12)
Proceeding as before, the following three solution sets are obtained:
Set 1.
,1122
2 CV ,24212 21 kAACCkkCV ,02 ,01
,1
1882412121212 222220
VABBCCkkAkkACkCV ,kk ,VV
,2
1132881616
22422222
3
1V
VCBABCABABCBV
C (6.13)
where k, V, A, B and C are arbitrary constants.
Set 2.
,1
1882412121212 222220
VABBCCkkACkAkkCV ,02 ,01
,243322212 32223321 BCkCkACkkAAkkBAkCBkV ,VV
,22222212 243223422422 BCkABkCkACkkAAkkBBkkCV
,2
1132881616
22422222
3
1V
VCBABCABABCBV
C ,kk (6.14)
where k, V, A, B and C are arbitrary constants.
Set 3.
,162
2 CV ,1
1828 20
VBABCV ,VV ,
)1(2
C
Ak ,01
,81632816)1(4
3 4222222
22 ABABCBBCACBC
,01 (6.15)
where V, A, B and C are arbitrary constants.
Substituting equations (6.13)-(6.15) in (6.12), the following solutions are attained:
170
.)/(112
)/(24212
11882412121212)(
22
2
222221
GGkCV
GGkkAACCkkCV
VABBCCkkAkkACkCVu
(6.16)
.)/()222
222(12)/(
243322212
11882412121212)(
224
3223422421
3222332
222222
GGkBCkABkCk
ACkkAAkkBBkkCVGGk
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
(6.17)
,)/()1(2
81632816)1(4
3
)/()1(2
161
)1828()(
2
4222222
2
2
223
GGC
A
ABABCBBCACBC
GGC
ACV
VBABCVu
(6.18) where Vtx ; V, A, B and C are arbitrary constants.
Inserting the solutions )(G of (1.49) in (6.16) and simplifying, we get
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
1112
)2/tanh(12
124212
11882412121212)(
2
2
2
2222211
AC
kCV
AC
kkAACCkkCV
VABBCCkkAkkACkCVu
171
Fig. 6.7. Solution 11u shows the graph of cuspon for .1,1,2,1,1 VkCBA
,)2/coth(12
1112
)2/coth(12
124212
11882412121212)(
2
2
2
2222221
AC
kCV
AC
kkAACCkkCV
VABBCCkkAkkACkCVu
Fig. 6.8. Illustrates exact singular soliton solution 21u for .1,1,2,1,1 VkCBA
172
,)(sec)tanh(12
1112
)(sec)tanh(12
124212
11882412121212)(
2
2
2
2222231
hiAC
kCV
hiAC
kkAACCkkCV
VABBCCkkAkkACkCVu
,)(csc)coth(12
1112
)(csc)coth(12
124212
11882412121212)(
2
2
2
2222241
hAC
kCV
hAC
kkAACCkkCV
VABBCCkkAkkACkCVu
,)4/coth()4/tanh(214
1112
)4/coth()4/tanh(214
1
24212
11882412121212)(
2
2
2
2222251
AC
kCV
AC
k
kAACCkkCV
VABBCCkkAkkACkCVu
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
1
24212
11882412121212)(
222
2
22
2
2222261
BF
FHFA
CkCV
BF
FHFA
Ck
kAACCkkCV
VABBCCkkAkkACkCVu
173
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
1
24212
11882412121212)(
222
2
22
2
2222271
BF
FHFA
CkCV
BF
FHFA
Ck
kAACCkkCV
VABBCCkkAkkACkCVu
where F and H are real constants.
,)2/cosh()2/sinh(
)2/cosh(2112
)2/cosh()2/sinh(
)2/cosh(224212
11882412121212)(
2
2
2
2222281
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
,)2/sinh()2/cosh(
)2/sinh(2112
)2/sinh()2/cosh(
)2/sinh(224212
11882412121212)(
2
2
2
2222291
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
174
Fig. 6.9. Solution 91u elucidates the soliton for ,2,1,1 CBA .1,1 Vk The
particular types of solitary waves are solitons. The soliton solution is a spatially confined solution, hence 0)(),(),( uuu as , .tVx An amazing chattel of
solitons is that it maintains its individuality upon interacting with other solitons.
,)cosh()sinh(
)cosh(2112
)cosh()sinh(
)cosh(224212
11882412121212)(
2
2
2
22222101
iA
BkCV
iA
BkkAACCkkCV
VABBCCkkAkkACkCVu
.)sinh()cosh(
)sinh(2112
)sinh()cosh(
)sinh(224212
11882412121212)(
2
2
2
22222111
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
175
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solution are
,)2/tan(12
1112
)2/tan(12
124212
11882412121212)(
2
2
2
22222121
AC
kCV
AC
kkAACCkkCV
VABBCCkkAkkACkCVu
Fig.6.10. Solution 121u represents the exact periodic traveling wave solution for
,2,1,1 CBA .1,1 Vk The traveling wave solutions which are periodic in nature
like )cos( tx are called periodic solutions.
,)2/cot(12
1112
)2/cot(12
124212
11882412121212)(
2
2
2
22222131
AC
kCV
AC
kkAACCkkCV
VABBCCkkAkkACkCVu
176
,)sec()tan(12
1112
)sec()tan(12
1
24212
11882412121212)(
2
2
2
22222141
AC
kCV
AC
k
kAACCkkCV
VABBCCkkAkkACkCVu
,)(csc)cot(12
1112
)(csc)cot(12
1
24212
11882412121212)(
2
2
2
22222151
hAC
kCV
hAC
k
kAACCkkCV
VABBCCkkAkkACkCVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
11882412121212)(
222
2
22
2
22222161
BF
FHFA
CkCV
BF
FHFA
Ck
kAACCkkCV
VABBCCkkAkkACkCVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
11882412121212)(
222
2
22
2
22222171
BF
FHFA
CkCV
BF
FHFA
Ck
kAACCkkCV
VABBCCkkAkkACkCVu
177
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
11882412121212)(
222
2
22
2
22222181
BF
FHFA
CkCV
BF
FHFA
Ck
kAACCkkCV
VABBCCkkAkkACkCVu
where F and H are real constants such that .022 HF
,)2/cos()2/sin(
)2/cos(2112
)2/cos()2/sin(
)2/cos(224212
11882412121212)(
2
2
2
22222191
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
,)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(224212
11882412121212)(
2
2
2
22222201
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
,)cos()sin(
)cos(2112
)cos()sin(
)cos(224212
11882412121212)(
2
2
2
22222211
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
178
.)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(224212
11882412121212)(
2
2
2
22222221
A
BkCV
A
BkkAACCkkCV
VABBCCkkAkkACkCVu
When 0B and 0)1( CA , the solutions are
,)sinh()cosh()1(
112
)sinh()cosh()1(24212
11882412121212)(
2
1
12
1
12
22222231
AAcC
AckCV
AAcC
AckkAACCkkCV
VABBCCkkAkkACkCVu
Fig.6.11. 231u represents the bell-shaped 2sec h solitary traveling wave solution for
,0,1 BA 1,1,2 VkC separated by infinite wings or infinite tails.
179
,)sinh()cosh()1(
))sinh()(cosh(112
)sinh()cosh()1(
))sinh()(cosh(24212
11882412121212)(
2
1
2
1
2
22222241
AAcC
AAAkCV
AAcC
AAAkkAACCkkCV
VABBCCkkAkkACkCVu
where 1c is an arbitrary constant.
When 0 BA and 0)1( C , the solution is
,)1(
1112
)1(
124212
11882412121212)(
2
2
2
2
2
22222251
cCkCV
cCkkAACCkkCV
VABBCCkkAkkACkCVu
where 2c is an arbitrary constant.
Similarly, inserting the solutions )(G of (1.49) in (6.17) and simplifying, we get
different families of exact solutions of (6.10) as follows.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(
12
1
22222212
)2/tanh(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
2222212
AC
k
BCkABkCkACkkAAkkBBkkCV
AC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
where Vtx ; k, A, B and C are arbitrary constants.
180
,)2/coth(
12
1
22222212
)2/coth(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
2222222
AC
k
BCkABkCkACkkAAkkBBkkCV
AC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
.))(sec)(tanh(
12
1
22222212
))(sec)(tanh(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
2222232
hiAC
k
BCkABkCkACkkAAkkBBkkCV
hiAC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
The other exact solutions of (6.10) are omitted for convenience.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(
12
1
22222212
)2/tan(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
22222122
AC
k
BCkABkCkACkkAAkkBBkkCV
AC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
181
Fig.6.12. Solution 122u represents the exact periodic traveling wave solution for
,2,1,1 CBA .1,2 Vk The traveling wave solutions which are periodic in
nature like )cos( tx are called periodic solutions.
,)2/cot(
12
1
22222212
)2/cot(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
22222132
AC
k
BCkABkCkACkkAAkkBBkkCV
AC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
.))sec()(tan(
12
1
22222212
))sec()(tan(12
1
243322212
11882412121212)(
2
24322342242
1
3222332
22222142
AC
k
BCkABkCkACkkAAkkBBkkCV
AC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
182
When 0 BA and 0)1( C , the solution of (6.10) is,
,)1(
1)2222
22(12)1(
1
243322212
11882412121212)(
2
2
243
22342242
1
2
3222332
22222252
cCkBCkABkCkACk
kAAkkBBkkCVcC
k
BCkCkACkkAAkkBAkCBkV
VABBCCkkACkAkkCVu
where 2c is an arbitrary constant.
The other exact solutions of (6.10) are omitted here for the sake of simplicity.
Lastly, surrogating the solutions )(G of (1.49) in (6.18) and simplifying, the solutions
of (6.10) are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1
81632816)1(4
3
))2/tanh(()1(2
116
1)1828()(
2
4222222
2
2
2213
C
ABABCBBCACBC
CCV
VBABCVu
where Vtx ; A, B and C are arbitrary constants.
,))2/coth(()1(2
1
81632816)1(4
3
))2/coth(()1(2
116
1)1828()(
2
4222222
2
2
2223
C
ABABCBBCACBC
CCV
VBABCVu
183
.)(sec)(tanh()1(2
1
81632816)1(4
3
)(sec)(tanh()1(2
116
1)1828()(
2
4222222
2
2
2233
hiC
ABABCBBCACBC
hiC
CVV
BABCVu
The others exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tan(()1(2
1
81632816)1(4
3
))2/tan(()1(2
116
1)1828()(
2
4222222
2
2
22123
C
ABABCBBCACBC
CCV
VBABCVu
Fig.6.13. 123u represents the exact singular periodic traveling wave solution for
.1,2,1,1 VCBA
184
,))2/cot(()1(2
1
81632816)1(4
3
))2/cot(()1(2
116
1)1828()(
2
4222222
2
2
22133
C
ABABCBBCACBC
CCV
VBABCVu
.)(sec)(tan()1(2
1
81632816)1(4
3
)(sec)(tan()1(2
116
1)1828()(
2
4222222
2
2
22143
C
ABABCBBCACBC
CCV
VBABCVu
When 0)1( C and 0 BA , the solution of (6.10) is
,)1(
1
)1(281632816
)1(4
3
)1(
1
)1(216
1)1828()(
2
2
4222222
2
2
2
22253
cCC
AABABCBBCACB
CcCC
ACV
VBABCVu
where 2c is an arbitrary constant.
Other exact solutions of (6.10) are omitted for convenience.
Example 6.2.3. The Boussinesq System
Consider the well-known Boussinesq system [216] in the form,
,0
,02
xxxxt
xt
buuav
vu (6.19)
This system of equations is used to model two-way propagation of certain water waves in
a homogeneous horizontal channel filled with an irrotational and inviscid liquid [184].
Now, using the traveling wave variable (1.45) that converts (6.19) into a system of ODEs
.0,,0
,0
2
baubuavV
vuV (6.20)
185
Integrating the system (6.20) once, we find
,
,
12 CubauVv
Vuv
(6.21)
where 1C is an integration constant. Substituting first equation of the system (6.21) into
second equation, we obtain
.0122 CubauuV (6.22)
Now, considering the homogeneous balance between u and 2u in (6.22), we obtain
.2m Therefore, the trial solution becomes
2
210
1
1
2
2 )()()()()(
kkkku .(6.23)
Proceeding as before, three solution sets are obtained as follows:
Set 1.
,
162
2a
Cb
,
2426 2
1a
kAACCkkCb ,VV ,kk ,01 ,02
,2
882412121212 222222
0a
VbAbBbBCbCkbkAbkbkACkbC
,4
32881616 42242222222222
1a
VCBbAbBCAbBAbBbCBbC
(6.24)
where k, V, A, B and C are arbitrary constants.
Set 2.
,2
882412121212 222222
0a
VbAbBbBCbCkbkACbkAbkkbC
,24332226 3222332
1a
BCkCkACkkAAkkBAkCBkb
,
2222226 24322342242
2a
BCkABkCkACkkAAkkBBkkCb
,02 01 , ,VV ,kk (6.25)
,4
32881616 42242222222222
1a
VCBbAbBCAbBAbBbCBbC
where k, V, A, B and C are arbitrary constants.
186
Set 3.
,
162
2a
Cb ,
2
828 22
0a
VbBbAbBC ,VV ,
)1(2
C
Ak ,01
,
)1(8
8163281632
4222222
2
Ca
ABABCBBCACBb ,01 (6.26)
,4
12812851216256256 42222224222222
1a
VBAbBCAbCBbAbBbCBbC
where V, A, B and C are arbitrary constants.
Substituting equations (6.24)-(6.26) in (6.23) yields
.)/(16
)/(2426
2
882412121212)(
222
222222
1
GGka
CbGGk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
(6.27)
.)/()222
222(6
)/(
24332226
2
882412121212)(
224
3223422421
3222332
222222
2
GGkBCkABkCk
ACkkAAkkBBkkCa
bGGk
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
(6.28)
,)/(
)1(2)1(8
816328163
)/()1(2
16
2
828)(
2
2
4222222
2222
3
GGC
A
Ca
ABABCBBCACBb
GGC
A
a
Cb
a
VbBbAbBCu
(6.29)
where Vtx ; k, V, A, B and C are arbitrary constants.
187
Inserting the solutions )(G of (1.49) in (6.27) and simplifying, the solutions are
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
116
)2/tanh(12
12426
2
882412121212)(
22
2
22222211
AC
ka
Cb
AC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
Fig. 6.14. 11u shows the graph of cuspon for .1,1,1,1,2,1,1 VbakCBA
Cuspons are diverse forms of solitons where solution shows cusps at their crests. Unlike
peakons where the derivatives at the peak differ only by a sign, the derivatives at the
jump of a cuspon diverge.
,)2/coth(12
116
)2/coth(12
12426
2
882412121212)(
22
2
22222221
AC
ka
Cb
AC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
188
,)(sec)tanh(12
116
)(sec)tanh(12
12426
2
882412121212)(
22
2
22222231
hiAC
ka
Cb
hiAC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)(csc)coth(12
116
)(csc)coth(12
12426
2
882412121212)(
22
2
22222241
hAC
ka
Cb
hAC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)4/coth()4/tanh(214
116
)4/coth()4/tanh(214
12426
2
882412121212)(
22
2
22222251
AC
ka
Cb
AC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)sinh(
)cosh()(
12
116
)sinh(
)cosh()(
12
1
2426
2
882412121212)(
2222
22
2
22222261
BF
FHFA
Ck
a
Cb
BF
FHFA
Ck
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
189
,)sinh(
)cosh()(
12
116
)sinh(
)cosh()(
12
1
2426
2
882412121212)(
2222
22
2
22222271
BF
FHFA
Ck
a
Cb
BF
FHFA
Ck
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
where F and H are real constants.
,
)2/cosh()2/sinh(
)2/cosh(216
)2/cosh()2/sinh(
)2/cosh(22426
2
882412121212)(
22
2
22222281
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,
)2/sinh()2/cosh(
)2/sinh(216
)2/sinh()2/cosh(
)2/sinh(22426
2
882412121212)(
22
2
22222291
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
190
Fig.6.15. Solution 91u explains the soliton for ,2,1,1 CBA .1,3,1,1 Vbak
Solitons are meticulous kinds of solitary waves. The soliton solution is a spatially confined solution, hence 0)(),(),( uuu as , .tVx An amazing
chattel of solitons is that it maintains its individuality upon interacting with other solitons.
,
)cosh()sinh(
)cosh(216
)cosh()sinh(
)cosh(22426
2
882412121212)(
22
2
222222101
iA
Bk
a
Cb
iA
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
.
)sinh()cosh(
)sinh(216
)sinh()cosh(
)sinh(22426
2
882412121212)(
22
2
222222111
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
191
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(12
116
)2/tan(12
12426
2
882412121212)(
22
2
222222121
AC
ka
Cb
AC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
Fig.6.16. 121u represents the exact periodic traveling wave solution for
,1,2,2,1,1 akCBA .1,3 Vb
,)2/cot(12
116
)2/cot(12
12426
2
882412121212)(
22
2
222222131
AC
ka
Cb
AC
ka
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
192
,)sec()tan(12
116
)sec()tan(12
1
2426
2
882412121212)(
22
2
222222141
AC
ka
Cb
AC
k
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)(csc)cot(12
116
)(csc)cot(12
1
2426
2
882412121212)(
22
2
222222151
hAC
ka
Cb
hAC
k
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)sin(
)cos()(
12
116
)sin(
)cos()(
12
1
2426
2
882412121212)(
2222
22
2
222222161
BF
FHFA
Ck
a
Cb
BF
FHFA
Ck
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,)sin(
)cos()(
12
116
)sin(
)cos()(
12
1
2426
2
882412121212)(
2222
22
2
222222171
BF
FHFA
Ck
a
Cb
BF
FHFA
Ck
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
193
,)sin(
)cos()(
12
116
)sin(
)cos()(
12
1
2426
2
882412121212)(
2222
22
2
222222181
BF
FHFA
Ck
a
Cb
BF
FHFA
Ck
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
where F and H are real constants such that .022 HF
,
)2/cos()2/sin(
)2/cos(216
)2/cos()2/sin(
)2/cos(22426
2
882412121212)(
22
2
222222191
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,
)2/sin()2/cos(
)2/sin(216
)2/sin()2/cos(
)2/sin(22426
2
882412121212)(
22
2
222222201
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
,
)cos()sin(
)cos(216
)cos()sin(
)cos(22426
2
882412121212)(
22
2
222222211
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
194
.
)2/sin()2/cos(
)2/sin(216
)2/sin()2/cos(
)2/sin(22426
2
882412121212)(
22
2
222222221
A
Bk
a
Cb
A
Bk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
When 0B and 0)1( CA , the solutions are
,)sinh()cosh()1(
16
)sinh()cosh()1(
2426
2
882412121212)(
2
1
1
2
1
12
222222231
AAcC
Ack
a
Cb
AAcC
Ack
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
Fig.6.17. 231u represents the bell-shaped 2sec h solitary traveling wave solution for
1,3,1,1,2,0,1 VbakCBA alienated by infinite wings or infinite tails.
195
,)sinh()cosh()1(
))sinh()(cosh(16
)sinh()cosh()1(
))sinh()(cosh(2426
2
882412121212)(
2
1
2
1
2
222222241
AAcC
AAAk
a
Cb
AAcC
AAAk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
where 1c is an arbitrary constant.
When 0 BA and 0)1( C , the solution of (6.19) is
,
)1(
116
)1(
12426
2
882412121212)(
2
2
2
2
2
222222251
cCk
a
Cb
cCk
a
kAACCkkCb
a
VbAbBbBCbCkbkAbkbkACkbCu
where 2c is an arbitrary constant.
Surrogating the solutions )(G of (1.49) in (6.27) and simplifying, the solutions are
When 0442 BBCA and 0)1( CA (or 0)1( CB )
,)2/tanh(
12
1
2222226
)2/tanh(12
1
24332226
2
882412121212)(
2
24322342242
1
3222332
22222212
AC
k
a
BCkABkCkACkkAAkkBBkkCb
AC
k
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
where Vtx ; k, A, B and C are arbitrary constants.
196
,)2/coth(
12
1
2222226
)2/coth(12
1
24332226
2
882412121212)(
2
24322342242
1
3222332
22222222
AC
k
a
BCkABkCkACkkAAkkBBkkCb
AC
k
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
.))(sec)(tanh(
12
1
2222226
))(sec)(tanh(12
1
24332226
2
882412121212)(
2
24322342242
1
3222332
22222232
hiAC
k
a
BCkABkCkACkkAAkkBBkkCb
hiAC
k
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
The other solutions of (6.19) are omitted for convenience.
When 0442 BBCA and 0)1( CA (or 0)1( CB ),
,)2/tan(
12
1)2222
22(6
)2/tan(12
1
24332226
2
882412121212)(
2
24322
342242
1
3222332
222222122
AC
kBCkABkCkACkkA
AkkBBkkCa
bA
Ck
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
197
,)2/cot(
12
1
2222226
)2/cot(12
1
24332226
2
882412121212)(
2
24322342242
1
3222332
222222132
AC
k
a
BCkABkCkACkkAAkkBBkkCb
AC
k
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
Fig.6.18. Solution 132u represents the exact periodic traveling wave solution for
,2,1,1 CBA .1,5,1,1 Vbak The traveling wave solutions which are
periodic in nature like )cos( tx are called periodic solutions.
.))sec()(tan(
12
1
2222226
))sec()(tan(12
1
24332226
2
882412121212)(
2
24322342242
1
3222332
222222142
AC
k
a
BCkABkCkACkkAAkkBBkkCb
AC
k
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
198
When 0 BA and 0)1( C , the solution of (6.19) is
,)1(
1)222
222(6
)1(
1
24332226
2
882412121212)(
2
2
24
322342242
1
2
3222332
222222252
cCkBCkABkCk
ACkkAAkkBBkkCa
b
cCk
a
BCkCkACkkAAkkBAkCBkb
a
VbAbBbBCbCkbkACbkAbkkbCu
where 2c is an arbitrary constant.
Finally, substituting the solutions )(G of (1.49) in (6.27) and simplifying, the solutions
of (6.19) are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ),
,))2/tanh(()1(2
1
)1(8
816328163
))2/tanh(()1(2
116
2
828)(
2
2
4222222
222213
C
Ca
ABABCBBCACBb
Ca
Cb
a
VbBbAbBCu
where Vtx ; A, B and C are arbitrary constants.
,))2/coth(()1(2
1
)1(8
816328163
))2/coth(()1(2
116
2
828)(
2
2
4222222
222223
C
Ca
ABABCBBCACBb
Ca
Cb
a
VbBbAbBCu
199
.)(sec)(tanh()1(2
1
)1(8
816328163
)(sec)(tanh()1(2
116
2
828)(
2
2
4222222
222233
hiC
Ca
ABABCBBCACBb
hiCa
Cb
a
VbBbAbBCu
The other exact solutions of the family are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tan(()1(2
1
)1(8
816328163
))2/tan(()1(2
116
2
828)(
2
2
4222222
2222123
C
Ca
ABABCBBCACBb
Ca
Cb
a
VbBbAbBCu
Fig.6.19. Solution 123u represents the exact singular periodic traveling wave solution for
.1,3,1,2,1,1 VbaCBA
200
,))2/cot(()1(2
1
)1(8
816328163
))2/cot(()1(2
116
2
828)(
2
2
4222222
2222133
C
Ca
ABABCBBCACBb
Ca
Cb
a
VbBbAbBCu
.)(sec)(tan()1(2
1
)1(8
816328163
)(sec)(tan()1(2
116
2
828)(
2
2
4222222
2222143
C
Ca
ABABCBBCACBb
Ca
Cb
a
VbBbAbBCu
When 0)1( C and 0 BA , the solution of (6.19) is
,
)1(
1
)1(2)1(8
816328163
)1(
1
)1(2
16
2
828)(
2
22
4222222
2
2
222253
cCC
A
Ca
ABABCBBCACBb
cCC
A
a
Cb
a
VbBbAbBCu
where 2c is an arbitrary constant.
Other exact solutions of (6.19) are omitted for convenience.
The value of v (which are not shown here for the sake of simplicity) can be
premeditated by substituting the values of u in the first equation of the system (6.21).
201
Example 6.2.4. The (3 + 1)-Dimensional Burgers Equations
Now consider the (3 + 1)-dimensional Burgers equations [219] in the form,
,
,
,
yz
yx
zzyyxxxxxt
wu
vu
uuucwubvuauuu
(6.30)
where cba and, are nonzero constants. The (3 + 1)-dimensional Burgers equations crop
up in various areas of applied mathematics, such as modeling of gas dynamics and traffic
flow.
The wave variable Vtzyxuu ),( converts the system (6.30) into a system of
ordinary differential equations as
,
,
,3
wu
vu
uucwubvuauVu
(6.31)
where prime stands for ordinary derivatives with respect to . Integrating the last two
equations of system (6.31) once, gives ,wvu and constants of integration are taken
as zero. The first equation in the system (6.31) after integrating once becomes:
.032
12
Cuu
cbaVu (6.32)
where 1C is an integration constant. Now, considering the homogeneous balance between
u and 2u in (6.32), we deduce that 12 mm . i.e. 1m . Therefore, the trial solution
becomes,
)()()( 10
1
1
kku . (6.33)
Proceeding as before the following three solution sets are obtained:
Set 1.
,)1(6
1cba
C
,00 ,01 ,kk 0)()1(63 cbaCkAV ,
,)3612121236
2666223612
121236367236()(2
1
20
22220
220
2000
20000
20
20
20
002
1
cCkbackakbkACk
abAcAbAabccakckC
akCbkCBkACkBCcba
C
(6.34)
202
where 0 , k, A, B and C are arbitrary constants.
Set 2.
,)(6 22
1cba
kAkCkB
00 , 01 , kk , 0)(663 cbakCkAV ,
,)3612121236
6662223612
121236367236()(2
1
2220
220
220
2000
00020
20
20
20
002
1
CkcbackbkakACk
AcAbAaabbccakckC
akCbkCBkACkBCcba
C
(6.35)
where 0 , k, A, B and C are arbitrary constants.
Set 3.
,)1(6
1cba
C
,
)1)((2
)44(3 2
1Ccba
BABC
,00 ,
)1(2 C
Ak
,)( 0cbaV
,)36222144144()(2
1 220
220
220
220
20
201 AcbacabcabBBC
cbaC
(6.36)
where 0 , A, B and C are arbitrary constants.
Substituting equations (6.34)-(6.36) in solution formula (6.33) yields:
,)/()1(6
)( 01 GGkcba
Cu
(6.37)
,)/()(6
)(1
22
02
GGd
cba
kAkCkBu (6.38)
,)/()1(2)1)((2
)44(3
)/()1(2
)1(6)(
12
03
GGC
A
Ccba
BABC
GGC
A
cba
Cu
(6.39)
where Vtzyx ; 0 , k, A, B and C are arbitrary constants.
Inserting the solutions )(G of (1.49) in (6.37) and simplifying, the following solutions
of system (6.30) are obtained:
203
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tanh(
)1(2
1)1(6)( 0
11
A
Ck
cba
Cu
Fig. 6.20. Shows the form of the exact kink-type solution of 11u for ,2,1,1 CBA
,1,1 ak .,1,1,1 0 zyxcb Kink waves are traveling waves which take
place from one asymptotic state to another. The kink solution approaches a constant at infinity.
,)2
1(cot
)1(2
1)1(6)( 0
21
hA
Ck
cba
Cu
,)(sec)(tan)1(2
1)1(6)( 0
31
hihA
Ck
cba
Cu
,)(csc)(cot)1(2
1)1(6)( 0
41
hhA
Ck
cba
Cu
,)4
1coth()
4
1(tan2
)1(4
1)1(6)( 0
51
hA
Ck
cba
Cu
,)sinh(
)(cos)(
)1(2
1)1(6)(
22
061
HF
hFHFA
Ck
cba
Cu
204
,)sinh(
)(cos)(
)1(2
1)1(6)(
22
071
HF
hFHFA
Ck
cba
Cu
where F and H are real constants.
,
)2
1cosh()
2
1sinh(
)2
1(cos2
)1(6)( 0
81
A
hBk
cba
Cu
,
)2
1sinh()
2
1cosh(
)2
1(sin2
)1(6)( 0
91
A
hBk
cba
Cu
,)cosh()sinh(
)(cos2)1(6)( 0
101
iA
hBk
cba
Cu
.)sinh()cosh(
)(sin2)1(6)( 0
111
A
hBk
cba
Cu
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tan(
)1(2
1)1(6)( 0
121
A
Ck
cba
Cu
Fig.6.21. Solution 121u represents the exact periodic traveling wave solution for
.,1,1,1,1,1,2,1,1 0 zyxcbakCBA The traveling wave
solutions which are periodic in nature like )cos( tx are called periodic solutions.
205
,)2
1(cot
)1(2
1)1(6)( 0
131
A
Ck
cba
Cu
,)sec()tan()1(2
1)1(6)( 0
141
A
Ck
cba
Cu
,)csc)cot()1(2
1)1(6)( 0
151
A
Ck
cba
Cu
,)4
1cot()
4
1tan(2
)1(4
1)1(6)( 0
161
A
Ck
cba
Cu
,)sin(
)cos()(
)1(2
1)1(6)(
22
0171
HF
FHFA
Ck
cba
Cu
,)sin(
)cos()(
)1(2
1)1(6)(
22
0181
HF
FHFA
Ck
cba
Cu
where F and H are arbitrary constants such that 022 HF .
,
)2
1cos()
2
1sin(
)2
1(cos2
)1(6)( 0
191
A
Bk
cba
Cu
,
)2
1sin()
2
1cos(
)2
1sin(2
)1(6)( 0
201
A
Bk
cba
Cu
,)cos()sin(
)(cos2)1(6)( 0
211
A
Bk
cba
Cu
.
)2
1sin()
2
1cos(
)2
1sin(2
)1(6)( 0
221
A
Bk
cba
Cu
When 0B and 0)1( CA , the solutions are
,
)sinh()cosh()1(
)1(6)(
1
10
231
AAcC
Ack
cba
Cu
206
,)sinh()cosh()1(
)sinh()cosh()1(6)(
1
0241
AAcC
AAAk
cba
Cu
where 1c is an arbitrary constant.
When 0)1( C and 0 BA , the solution of system (6.30) is
,)1(
1)1(6)(
2
0251
cCk
cba
Cu
where 2c is an arbitrary constant.
Surrogating the solutions )(G of (1.49) in (6.38) and simplifying, the solutions of
system (6.30) are:
,)2
1tanh(
)1(2
1)(6)(
122
012
A
Ck
cba
kAkCkBu
where Vtzyx ; 0 , k, A, B and C are arbitrary constants.
,)2
1coth(
)1(2
1)(6)(
122
022
A
Ck
cba
kAkCkBu
.)(sec)tanh()1(2
1)(6)(
122
032
hiA
Ck
cba
kAkCkBu
The other solutions of system (6.30) are omitted for convenience.
When 0442 BBCA and 0)1( CA (or 0)1( CB ),
,)2
1tan(
)1(2
1)(6)(
122
0122
A
Ck
cba
kAkCkBu
,)2
1cot(
)1(2
1)(6)(
122
0132
A
Ck
cba
kAkCkBu
.)sec()tan()1(2
1)(6)(
122
0142
A
Ck
cba
kAkCkBu
207
When 0)1( C and 0 BA , the solution of system (6.30) is
,)1(2
1)(6)(
1
2
22
0252
cCk
cba
kAkCkBu
where 2c is an arbitrary constant.
Lastly, surrogating the solutions )(G of (1.49) into (6.39) and simplifying, the solutions
of system (6.30) are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tanh(
)1)((4
)44(3)
2
1tanh(
3)(
1
2
2
013
Ccba
BABC
cbau
where Vtzyx ; 0 , A, B and C are arbitrary constants.
,)2
1coth(
)1)((4
)44(3)
2
1coth(
3)(
1
2
2
023
Ccba
BABC
cbau
,)(sec)tanh()1)((4
)44(3
)(sec)tanh(3
)(
1
2
2
033
hiCcba
BABC
hicba
u
The other exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tan(
)1)((4
)44(3)
2
1tan(
3)(
1
2
2
0123
Ccba
BABC
cbau
,)2
1cot(
)1)((4
)44(3)
2
1cot(
3)(
1
2
2
0133
Ccba
BABC
cbau
.)sec()tan()1)((4
)44(3
)sec()tan(3
)(
1
2
2
0143
Ccba
BABC
cbau
208
When 0)1( C and 0 BA , the solution of system (6.30) is
,1
2)1)((2
)44(31
2
6)(
1
22
2
2
0253
c
A
Ccba
BABC
c
A
cbau
where 2c is an arbitrary constant.
Example 6.2.5. The (3 + 1) Dimensional Modified KdV-ZK Equation
Finally, consider the (3 + 1)-dimensional modified KdV-ZK equation [232] in the form
,02 zzxyyxxxxxt uuuuuu (6.40)
Now, using the wave transformation tVzyxutzyxu ),(),,,( that permits to
convert (6.40) in an ordinary differential equation as
,032 uuuuV (6.41)
where prime denotes ordinary derivatives with respect to . Integrating (6.41) once with
respect yields:
,033
1 31 uuVuC (6.42)
where 1C is an integral constant which is to be determined later. Now, cconsidering the
homogeneous balance between u and 3u in (6.42), we deduce that .23 mm i.e.
.1m Therefore, the trial solution becomes,
.)()()( 10
1
1
kku (6.43)
Proceeding as before the following four solution sets are obtained.
Set 1.
,
2
223,
2
)1(601
CkkAiCi
,01 ,kk
,0,2
366 1
2 CABBCV (6.44)
where k, , A, B and C are arbitrary constants.
209
Set 2.
,0,2
366
,,2
6,
2
223,0
12
22
101
CABBCV
kkkBCkAkiCkkAi
(6.45)
where k, , A, B and C are arbitrary constants.
Set 3.
,0,446
,12
,122
443,0,
2
)1(6
12
2
101
CBBCAV
C
Ak
C
BBCAiCi
(6.46)
where , A, B and C are arbitrary constants.
Set 4.
,122
3,
2
423,
2
)1(6 22
101
C
kBCkAkiCkkAiCi
,2
312181812181836, 22222 ABAkkBCACkkCCkVkk (6.47)
,
2
122136 2
1
BAkkCAkCCiC
where k, , A, B and C are arbitrary constants.
Substituting equations (6.44)-(6.47) into (6.43), the solution becomes
,)/(2
)1(6
2
223)(1 GGk
CiCkkAiu
(6.48)
where .2
366 2 tABBCzyx
,)/(2
6
2
223)(
122
2
GGdkBCkAkiCkkAi
u
(6.49)
where .2
366 2 tABBCzyx
,)/()1(2122
443)/(
)1(22
)1(6)(
12
3
GG
C
A
C
BBCAiGG
C
ACiu
(6.50)
210
where .446 2 tBBCAzyx
,)/(122
3
)/(2
)1(6
2
423)(
122
4
GGkC
kBCkAki
GGkCiCkkAi
u
(6.51)
where .2
312181812181836 22222 tABAkkBCACkkCCkzyx
Inserting the solutions )(G of (1.49) in (6.48) and simplifying, the following solutions
of (6.40) are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)
2
1tanh(
)1(2
1
2
)1(6
2
223)(1
1
A
Ck
CiCkkAiu
where .2
366 2 tABBCzyx
,)
2
1(cot
)1(2
1
2
)1(6
2
223)(2
1
hA
Ck
CiCkkAiu
Fig.6.22.Solution 21u explicates the soliton for ,0,9,2,5.0,1,3 ykCBA
.0z The particular types of solitary waves are solitons. The soliton solution is a spatially confined solution; hence 0)(),(),( uuu as , .tVx An
amazing chattel of solitons is that it maintains its individuality upon interacting with other solitons.
211
,)(sec)(tan)1(2
1
2
)1(6
2
223)(3
1
hihAC
kCiCkkAi
u
,)(csc)(cot)1(2
1
2
)1(6
2
223)(4
1
hhAC
kCiCkkAi
u
,)
4
1coth()
4
1(tan2
)1(4
1
2
)1(6
2
223)(5
1
hA
Ck
CiCkkAiu
,)sinh(
)(cos)(
)1(2
1
2
)1(6
2
223)(
22
61
HF
hFHFA
Ck
CiCkkAiu
,
)sinh(
)(cos)(
)1(2
1
2
)1(6
2
223)(
2271
HF
hFHFA
Ck
CiCkkAiu
where F and H are real constants.
,
)2
1cosh()
2
1sinh(
)2
1(cos2
2
)1(6
2
223)(8
1
A
hBk
CiCkkAiu
,
)2
1sinh()
2
1cosh(
)2
1(sin2
2
)1(6
2
223)(9
1
A
hBk
CiCkkAiu
,
)cosh()sinh(
)(cos2
2
)1(6
2
223)(10
1
iA
hBk
CiCkkAiu
.
)sinh()cosh(
)(sin2
2
)1(6
2
223)(11
1
A
hBk
CiCkkAiu
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)
2
1tan(
)1(2
1
2
)1(6
2
223)(12
1
A
Ck
CiCkkAiu
212
Fig.6.23. 121u represents the exact periodic traveling wave solution for ,5.1,2 BA
,)
2
1(cot
)1(2
1
2
)1(6
2
223)(13
1
A
Ck
CiCkkAiu
Fig. 6.24. Solution 131u explains the soliton for ,0,9,2,5.0,5.1,2 ykCBA
.0z Solitons are particular kinds of solitary waves. An amazing chattel of solitons is that it maintains its individuality upon interacting with other solitons.
,)sec()tan()1(2
1
2
)1(6
2
223)(14
1
AC
kCiCkkAi
u
,)csc)cot()1(2
1
2
)1(6
2
223)(15
1
AC
kCiCkkAi
u
213
,)
4
1cot()
4
1tan(2
)1(4
1
2
)1(6
2
223)(16
1
A
Ck
CiCkkAiu
,
)sin(
)cos()(
)1(2
1
2
)1(6
2
223)(
22
171
HF
FHFA
Ck
CiCkkAiu
,
)sin(
)cos()(
)1(2
1
2
)1(6
2
223)(
22
181
HF
FHFA
Ck
CiCkkAiu
where F and H are arbitrary constants such that 022 HF .
,
)2
1cos()
2
1sin(
)2
1(cos2
2
)1(6
2
223)(19
1
A
Bk
CiCkkAiu
,
)2
1sin()
2
1cos(
)2
1sin(2
2
)1(6
2
223)(20
1
A
Bk
CiCkkAiu
,
)cos()sin(
)(cos2
2
)1(6
2
223)(21
1
A
Bk
CiCkkAiu
.
)2
1sin()
2
1cos(
)2
1sin(2
2
)1(6
2
223)(22
1
A
Bk
CiCkkAiu
When 0B and 0)1( CA , the solutions are
,)sinh()cosh()1(2
)1(6
2
223)(
1
1231
AAcC
Ack
CiCkkAiu
,)sinh()cosh()1(
)sinh()cosh(
2
)1(6
2
223)(
1
241
AAcC
AAAk
CiCkkAiu
where 1c is an arbitrary constant.
When 0)1( C and 0 BA , the solution of (6.40) is
,
)1(
1
2
)1(6
2
223)(
2
251
Cck
CiCkkAiu
where 2c is an arbitrary constant.
Similarly, surrogating the solutions )(G of the (1.43) in (6.49) and simplifying, the
solutions of (6.40) are:
214
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)
2
1tanh(
)1(2
1
2
6
2
223)(
12212
A
Ck
kBCkAkiCkkAiu
where .2
366 2 tABBCzyx
,)
2
1coth(
)1(2
1
2
6
2
223)(
12222
A
Ck
kBCkAkiCkkAiu
.)(sec)tanh()1(2
1
2
6
2
223)(
12232
hiA
Ck
kBCkAkiCkkAiu
The other exact solutions of (6.40) are omitted for the sake of convenience.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)
2
1tan(
)1(2
1
2
6
2
223)(
122122
A
Ck
kBCkAkiCkkAiu
Fig.6.25. Solution 122u represents the exact periodic traveling wave solution for
,5.1,2 BA ,0C .0,0,9,1 zyk
215
,)
2
1cot(
)1(2
1
2
6
2
223)(
122132
A
Ck
kBCkAkiCkkAiu
,)sec()tan()1(2
1
2
6
2
223)(
122142
AC
kkBCkAkiCkkAi
u
When 0)1( C and 0 BA , the solution of (6.40) is
,
)1(
1
2
6
2
223)(
1
2
22252
Cck
kBCkAkiCkkAiu
where 2c is an arbitrary constant.
Similarly, surrogating the solutions )(G of (1.49) in (6.50) and simplifying, we obtain
the following solutions of (6.40):
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tanh(
122
443)
2
1tanh(
2
)1(6)(
1213
C
BBCAiCiu
where .446 2 tBBCAzyx
,)2
1coth(
122
443)
2
1coth(
2
)1(6)(
1223
C
BBCAiCiu
.)(sec)tanh(
122
443)(sec)tanh(
2
)1(6)(
1
233
hi
C
BBCAihi
Ciu
The other exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tan(
122
443)
2
1tan(
2
)1(6)(
12123
C
BBCAiCiu
,)2
1cot(
122
443)
2
1cot(
2
)1(6)(
12133
C
BBCAiCiu
216
.)sec()tan(
122
443)sec()tan(
2
)1(6)(
1
2143
C
BBCAiCiu
When 0)1( C and 0 BA , the solution of (6.40) is
,
)1(
1
12122
443
1
1
122
)1(6)(
1
2
2
2
253
CcC
A
C
BBCAi
cCC
ACiu
where 2c is an arbitrary constant.
Lastly, surrogating the solutions )(G of (1.49) in (6.51) and simplifying, the following
solutions of (6.40) are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tanh(
)1(2
1
122
3
)2
1tanh(
)1(2
1
2
)1(6
2
423)(
122
14
AC
kC
kBCkAki
AC
kCiCkkAi
u
where .2
312181812181836 22222 tABAkkBCACkkCCkzyx
217
,)2
1coth(
)1(2
1
122
3
)2
1coth(
)1(2
1
2
)1(6
2
423)(
122
24
AC
kC
kBCkAki
AC
kCiCkkAi
u
.)(sec)tanh()1(2
1
122
3
)(sec)tanh()1(2
1
2
)1(6
2
423)(
122
34
hiAC
kC
kBCkAki
hiAC
kCiCkkAi
u
The other exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2
1tan(
)1(2
1
122
3
)2
1tan(
)1(2
1
2
)1(6
2
423)(
122
124
AC
kC
kBCkAki
AC
kCiCkkAi
u
Fig.6.27. Solution 124u represents the periodic traveling wave solution for
,1,1 BA ,2C .0,0,9,2 zyk
218
,)2
1cot(
)1(2
1
122
3
)2
1cot(
)1(2
1
2
)1(6
2
423)(
122
134
AC
kC
kBCkAki
AC
kCiCkkAi
u
.)sec()tan()1(2
1
122
3
)sec()tan()1(2
1
2
)1(6
2
423)(
122
144
AC
kC
kBCkAki
AC
k
CiCkkAiu
When 0)1( C and 0 BA , the solution of (6.40) is
,)1(
1
122
3
)1(
1
2
)1(6
2
423)(
1
2
22
2
254
Cck
C
kBCkAki
Cck
CiCkkAiu
where 2c is an arbitrary constant.
Discussion
Copious precise traveling wave solutions of a variety of nonlinear evolution equations
have been constructed by applying novel )/( GG -expansion method. The obtained
solutions are more general and many known solutions are only a special case of them,
when parameters are given some special values. Moreover, the novel )/( GG -expansion
method is relatively resourceful and virtually suitable in the discovery of exact solutions
of nonlinear evolution equations.
219
Chapter 7
Novel )/( GG -Expansion Method for Fractional Partial
Differential Equations
220
7.1. Introduction
Differential equations of non integer order are generalizations of conventional differential
equations of integer order. Exploration and applications of integrals and derivatives of
arbitrary order are efficiently dealt with the field of mathematical analysis, called as
fractional calculus, which has engrossed in considerable interest in many disciplines, now
a day. The behavior of many physical systems can be perfectly defined by the fractional
theory. In recent years, we cannot rebuff the importance of fractional differential
equations because of their numerous applications in the areas of physics and engineering.
Many important phenomena in electro-magnetic, acoustics, visco-elasticity, electro-
chemistry and material science are better described by differential equations of non
integer order. For example, the nonlinear fluctuation of earthquakes can be modeled with
the help of fractional derivatives and the fluid-dynamic traffic model with fractional
derivatives can eradicate the problems arising from the huge traffic flow [77, 164, 193,
229]. On account of development of the computer and its exact description of count-less
real-life problems, fractional calculus has touched the height of fame and success now a
day, although it was invented three centuries ago by Newton and Leibniz. Further
applications of differential equations of non integer order can be found in [155-163].
The exact solutions of nonlinear fractional partial differential equations have a great
importance in nonlinear sciences. In the past, many analytical and numerical methods
have been proposed to obtain solutions of nonlinear differential equations, such as
Variational Iteration [169], Differential Transform [182], Modified Adomian’s
Decomposition [7, 96, 100], Homotopy Perturbation [168] methods and so on. But most
of the developed techniques have their limitations coupled with some inbuilt deficiencies
like limited convergence, divergent results, linearization, discretization, unrealistic
assumptions, huge computational work and non-compatibility with the versatility of
physical problems.
In this chapter, Novel ( / )G G -expansion method is extended to find the soliton solutions
of non integer order partial differential equations [27, 201, 202]. In the proposed
algorithm the following complex transformation is used:
,, utxu
,11
0
t
Vx
L
221
The proposed technique has been applied on a wide range of nonlinear diversified
physical problems including, high-dimensional nonlinear evolution equations have been
taking the advantage of the proposed technique. The proposed scheme is having the
qualities of compatibility with the complexity of such problems is very user friendly and
numerical results are very fortifying.
7.2. Numerical Examples
In this section, novel ( / )G G -expansion method is extended to find the soliton solutions
of non integer order partial differential equations including, the time fractional simplified
modified Camassa-Holm (MCH) equation, the time fractional BBM-Burger’s equation
and the space-time fractional SRLW equation. Physical properties of several nonlinear
traveling wave solutions are examined by graphs which are obtained for various values
of .
7.2.1. The Time Fractional Simplified MCH Equation
Consider the following time fractional simplified modified Camassa-Holm equation
[201] in the form
,1,0,where,02 2 xtxxxt uuuuuD (7.1)
which is the variation of the equation
.0,where,02 2 xtxxxt uuuuu (7.2)
Equation (7.1) is converted into an ordinary differential equation of integer order by
using (1.6) and (1.52), and after integrating once yields:
,03
2 1
32 C
uLuVLuLV (7.3)
where 1C is an integral constant which is to be determined later.
Considering the homogeneous balance between u and 3u in (14), we obtain .23 mm
i.e. .1m Therefore the trial solution formula (1.54) becomes,
.)()()( 10
1
1
kku (7.4)
Using (7.4) in (7.3), left hand side is converted into polynomials in iGGk / and
,/i
GGk ).,,2,1,0( mi Equating the coefficients of same power of the resulted
222
polynomials to zero, a system of algebraic equations for 0 , 1 , 1 , k , 1C , L and V is
obtained. Solving the system, the following four solution sets are attained:
Set 1.
,
244
22622
0
BBCAL
CkkALi
,
244
16222
1
BBCAL
CLi
,
244
422
BBCAL
LV
kkLL , , ,01 ,01 C (7.5)
where k, L, A, B and C are arbitrary constants.
Set.2.
,
244
22622
0
BBCAL
CkkALi
,244
6222
22
1
BBCAL
BCkkkALi
,
244
422
BBCAL
LV
kkLL , , ,01 ,01 C (7.6)
where k, L, A, B and C are arbitrary constants.
Set 3.
,
1442
132
221
BBCAL
CLi
,114422
44322
2
1
CBBCAL
BBCALi
,
1442
222
BBCAL
LV
,
)1(2
C
Ak ,LL ,00 ,01 C (7.7)
where L, A, B and C are arbitrary constants
Set 4.
,12442
44622
2
1
CBBCAL
BBCALi
,
244
422
BBCAL
LV
,)1(2
C
Ak ,LL ,0,0 10 ,01 C (7.8)
where L, A, B and C are arbitrary constants.
Substituting equations (7.5)-(7.8) in (7.4), the solution formula (7.4) becomes,
223
,)/(
244
162
244
226)(
22221 GGk
BBCAL
CLi
BBCAL
CkkALiu
(7.9)
where
.1244
422
t
BBCAL
LLx
,)/(244
62
244
226)(
1
22
22
222
GGk
BBCAL
BCkkkALi
BBCAL
CkkALiu
(7.10)
where
.1244
422
t
BBCAL
LLx
,)/()1(2114422
443
)/()1(21442
132)(
1
22
2
223
GGC
A
CBBCAL
BBCALi
GGC
A
BBCAL
CLiu
(7.11)
where
.11442
222
t
BBCAL
LLx
,)/()1(212442
446)(
1
22
2
4
GG
C
A
CBBCAL
BBCALiu
(7.12)
where
.1244
422
t
BBCAL
LLx
Inserting the solutions )(G of (1.56) in (7.9) and simplifying, the solutions are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(
12
1
244
162
244
226)(
2222
11
AC
k
BBCAL
CLi
BBCAL
CkkALiu
224
Fig. 7.1 (a-d). Shows the form of the exact kink-type solution of 11u for different values
of and ,2,1,1 CBA .1,1,1,1 Lk Kink waves are traveling waves
which take place from one asymptotic state to another. The kink solution approaches a constant at infinity.
,)2/coth(
12
1
244
162
244
226)(
2222
21
AC
k
BBCAL
CLi
BBCAL
CkkALiu
225
Fig.7.2 (a-d): Singular kink solution of 21u for different values of and
,1,2,5 CBA .5,1,1,2 Lk
,)(sec)tanh(
12
1
244
162
244
226)(
2222
31
hiAC
k
BBCAL
CLi
BBCAL
CkkALiu
,)(csc)coth(
12
1
244
162
244
226)(
2222
41
hAC
k
BBCAL
CLi
BBCAL
CkkALiu
,)4/coth()4/tanh(2
14
1
244
162
244
226)(
2222
51
AC
k
BBCAL
CLi
BBCAL
CkkALiu
226
,
)sinh(
)cosh()(
12
1
244
162
244
226)(
22
2222
61
BF
FHFA
Ck
BBCAL
CLi
BBCAL
CkkALiu
,
)sinh(
)cosh()(
12
1
244
162
244
226)(
22
2222
71
BF
FHFA
Ck
BBCAL
CLi
BBCAL
CkkALiu
where F and H are real constants.
,)2/cosh()2/sinh(
)2/cosh(2
244
162
244
226)(
2222
81
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
,)2/sinh()2/cosh(
)2/sinh(2
244
162
244
226)(
2222
91
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
,)cosh()sinh(
)cosh(2
244
162
244
226)(
2222
101
iA
Bk
BBCAL
CLi
BBCAL
CkkALiu
.)sinh()cosh(
)sinh(2
244
162
244
226)(
2222
111
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
227
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(
12
1
244
162
244
226)(
2222
121
AC
k
BBCAL
CLi
BBCAL
CkkALiu
,)2/cot(
12
1
244
162
244
226)(
2222
131
AC
k
BBCAL
CLi
BBCAL
CkkALiu
,)sec()tan(
12
1
244
162
244
226)(
2222
141
AC
k
BBCAL
CLi
BBCAL
CkkALiu
,)(csc)cot(
12
1
244
162
244
226)(
2222
151
hAC
k
BBCAL
CLi
BBCAL
CkkALiu
,
)sin(
)cos()(
12
1
244
162
244
226)(
22
2222
161
BF
FHFA
Ck
BBCAL
CLi
BBCAL
CkkALiu
,
)sin(
)cos()(
12
1
244
162
244
226)(
22
2222
171
BF
FHFA
Ck
BBCAL
CLi
BBCAL
CkkALiu
228
,
)sin(
)cos()(
12
1
244
162
244
226)(
22
2222
181
BF
FHFA
Ck
BBCAL
CLi
BBCAL
CkkALiu
where F and H are real constants such that .022 HF
,)2/cos()2/sin(
)2/cos(2
244
162
244
226)(
2222
191
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
,)2/sin()2/cos(
)2/sin(2
244
162
244
226)(
2222
201
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
,)cos()sin(
)cos(2
244
162
244
226)(
2222
211
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
.)2/sin()2/cos(
)2/sin(2
244
162
244
226)(
2222
221
A
Bk
BBCAL
CLi
BBCAL
CkkALiu
When 0B and 0)1( CA , the solutions are
,
)sinh()cosh()1(
244
162
244
226)(
1
1
2222
231
AAcC
Ack
BBCAL
CLi
BBCAL
CkkALiu
229
,
)sinh()cosh()1(
))sinh()(cosh(
244
162
244
226)(
1
2222
241
AAcC
AAAk
BBCAL
CLi
BBCAL
CkkALiu
where 1c is an arbitrary constant.
When 0 BA and ,0)1( C the solution of (7.1) is
,)1(
1
244
162
244
226)(
2
2222
251
cCk
BBCAL
CLi
BBCAL
CkkALiu
where 2c is an arbitrary constant.
Inserting the solutions )(G of (1.56) in (7.10) and simplifying, the following solutions
are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(
12
1
244
62
244
226)(
1
22
22
22
12
AC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
,)2/coth(
12
1
244
62
244
226)(
1
22
22
22
22
AC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
.))(sec)(tanh(
12
1
244
62
244
226)(
1
22
22
22
32
hiAC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
230
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(
12
1
244
62
244
226)(
1
22
22
22
122
AC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
Fig.7.3 (a-d): Solution 122u represents the periodic traveling wave solution for different
values of and ,2,1,2 CBA .12,1,1,2 Lk
,)2/cot(
12
1
244
62
244
226)(
1
22
22
22
132
AC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
231
.))sec()(tan(
12
1
244
62
244
226)(
1
22
22
22
142
AC
k
BBCAL
BCkkkALi
BBCAL
CkkALiu
When 0 BA and 0)1( C , the solution of (7.1) is
,)1(
1
244
62
244
226)()(
1
2
22
22
222
252
cCk
BBCAL
BCkkkALi
BBCAL
CkkALiuu
where 2c is an arbitrary constant.
Similarly by inserting the solutions )(G of (1.56) in (7.11), the solutions are
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1
114422
443
))2/tanh(()1(2
1
1442
132)(
1
22
2
22
13
CCBBCAL
BBCALi
CBBCAL
CLiu
,))2/coth((
)1(2
1
114422
443
))2/coth(()1(2
1
1442
132)(
1
22
2
22
23
CCBBCAL
BBCALi
CBBCAL
CLiu
.)(sec)(tanh()1(2
1
114422
443
)(sec)(tanh()1(2
1
1442
132)(
1
22
2
22
33
hiCCBBCAL
BBCALi
hiCBBCAL
CLiu
The other exact solutions are omitted for the sake of simplicity.
232
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are:
,))2/tan((
)1(2
1
114422
443
))2/tan(()1(2
1
1442
132)(
1
22
2
22
123
CCBBCAL
BBCALi
CBBCAL
CLiu
Fig.7.4 (a-d): Illustrates the sketch of the singular periodic traveling wave solution of 123u
for different values of and ,2,1,1 CBA .9,1,1,2 Lk
,))2/cot((
)1(2
1
114422
443
))2/cot(()1(2
1
1442
132)(
1
22
2
22
133
CCBBCAL
BBCALi
CBBCAL
CLiu
233
.)(sec)(tan()1(2
1
114422
443
)(sec)(tan()1(2
1
1442
132)(
1
22
2
22
143
CCBBCAL
BBCALi
CBBCAL
CLiu
When 0)1( C and 0 BA , the solution of (7.1) is
,
)1(
1
)1(2114422
443
)1(
1
)1(21442
132)(
1
222
2
222
253
cCC
A
CBBCAL
BBCALi
cCC
A
BBCAL
CLiu
where 2c is an arbitrary constant.
Lastly, by surrogating the solutions )(G of (1.56) in (7.12), the solutions are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1
12442
446)(
1
22
214
CCBBCAL
BBCALiu
,))2/coth(()1(2
1
12442
446)(
1
22
224
CCBBCAL
BBCALiu
.)(sec)(tanh()1(2
1
12442
446)(
1
22
234
hi
CCBBCAL
BBCALiu
The other exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tan(()1(2
1
12442
446)(
1
22
2124
CCBBCAL
BBCALiu
,))2/cot(()1(2
1
12442
446)(
1
22
2134
CCBBCAL
BBCALiu
234
.)(sec)(tan()1(2
1
12442
446)(
1
22
2144
CCBBCAL
BBCALiu
When 0)1( C and 0 BA , the solution of (7.1) is
,)1(
1
)1(212442
446)(
1
222
2254
cCC
A
CBBCAL
BBCALiu
where 2c is an arbitrary constant.
7.2.2. The Time Fractional BBM-Burgers Equation
The BBM-Burgers equation [202] in time fractional form is
.10,0,02
2
t
uuuuD
x
xtxxt (7.13)
Utilizing (1.6) and (1.52) that converts (7.13) in an ordinary differential equation of
integer order and after integrating once yields,
,02
122 CuVLu
LuVL (7.14)
where 1C is an integration constant. Considering the homogeneous balance between
u and 2u in (7.14), we obtain .2m Therefore, the trial solution (1.54) becomes,
.)()()()()(2
210
1
1
2
2
kkkku (7.15)
Proceeding in a similar fashion as before, the following three solution sets are obtained:
Set 1.
,221121 AkkCCVL ,1122
2 CVL
kkLLVV ,, , ,01 ,02 (7.16)
,44442
1 22221 LVVLABCLVVLABC
LC
where k, L, V, A, B and C are arbitrary constants.
235
Set.2.
,
88112112 2222
0L
LVLABCBkCAkCV
,22112 21 AkCVLBkAkC
,11222
2 BkAkCVL kkLLVV ,, ,02 ,01 (7.17)
,44442
1 22221 LVLABCVLVLABCV
LC
where k, L, V, A, B and C are arbitrary constants.
Set 3.
,1122
2 CVL
,442 22
0L
LVABCVL
)1(2
C
Ak ,
,
14
4432
22
2C
ABCVL
,01 ,01 ,, LLVV (7.18)
,44
4444
448 2222
1
LVABCLV
LVABCLV
LC
where V, L, A, B and C are arbitrary constants.
Substituting equations (7.16)- (7.18) in (7.15), the trial solution (7.15) becomes,
,)/(112)/(22112
88112112)(
22
2222
1
GGkCVLGGkAkkCCVL
L
LVLABCBkCAkCVu
(7.19)
,)/(112
)/(22112
88112112)(
222
12
2222
2
GGkBkAkCVL
GGkAkCBkAkCVL
L
LVLABCBkCAkCVu
(7.20)
,)/()1(214
443
)/()1(2
112442
)(
2
2
22
2
222
3
GGC
A
C
ABCVL
GGC
ACVL
L
LVABCVLu
(7.21)
236
where
.1
tVLx
Inserting the solutions )(G of (1.56) in (7.19), the following solutions are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
1112
)2/tanh(12
122112
88112112)(
2
2
222211
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
,)2/coth(12
1112
)2/coth(12
122112
88112112)(
2
2
222221
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
25.0)a( 50.0)b(
237
75.0)c( 0.1)d(
Fig. 7.5 (a-d): Exact singular soliton solution of 21u for different values of and
,2,1,1 CBA .1,1,1 VLk
,)(sec)tanh(12
1112
)(sec)tanh(12
122112
88112112)(
2
2
2222
31
hiAC
kCVL
hiAC
kAkkCCVL
L
LVLABCBkCAkCVu
,)(csc)coth(12
1112
)(csc)coth(12
122112
88112112)(
2
2
222241
hAC
kCVL
hAC
kAkkCCVL
L
LVLABCBkCAkCVu
,)4/coth()4/tanh(214
1112
)4/coth()4/tanh(214
122112
88112112)(
2
2
222251
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
238
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
122112
88112112)(
222
2
22
222261
BF
FHFA
CkCVL
BF
FHFA
CkAkkCCVL
L
LVLABCBkCAkCVu
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
122112
88112112)(
222
2
222
222271
BF
FHFA
CkCVL
BF
FHFA
CkAkkCCVL
L
LVLABCBkCAkCVu
where F and H are real constants.
,)2/cosh()2/sinh(
)2/cosh(2112
)2/cosh()2/sinh(
)2/cosh(222112
88112112)(
2
2
222281
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
,)2/sinh()2/cosh(
)2/sinh(2112
)2/sinh()2/cosh(
)2/sinh(222112
88112112)(
2
2
222291
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
239
,)cosh()sinh(
)cosh(2112
)cosh()sinh(
)cosh(222112
88112112)(
2
2
2222101
iA
BkCVL
iA
BkAkkCCVL
L
LVLABCBkCAkCVu
.)sinh()cosh(
)sinh(2112
)sinh()cosh(
)sinh(222112
88112112)(
2
2
2222111
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(12
1112
)2/tan(12
122112
88112112)(
2
2
2222
121
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
,)2/cot(12
1112
)2/cot(12
122112
88112112)(
2
2
2222131
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
,)sec()tan(12
1112
)sec()tan(12
122112
88112112)(
2
2
2222141
AC
kCVL
AC
kAkkCCVL
L
LVLABCBkCAkCVu
240
,)(csc)cot(12
1112
)(csc)cot(12
122112
88112112)(
2
2
2222151
hAC
kCVL
hAC
kAkkCCVL
L
LVLABCBkCAkCVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
122112
88112112)(
222
2
22
2222
161
BF
FHFA
CkCVL
BF
FHFA
CkAkkCCVL
L
LVLABCBkCAkCVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
122112
88112112)(
222
2
22
2222
171
BF
FHFA
CkCVL
BF
FHFA
CkAkkCCVL
L
LVLABCBkCAkCVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
122112
88112112)(
222
2
22
2222181
BF
FHFA
CkCVL
BF
FHFA
CkAkkCCVL
L
LVLABCBkCAkCVu
where F and H are real constants such that .022 HF
241
,)2/cos()2/sin(
)2/cos(2112
)2/cos()2/sin(
)2/cos(222112
88112112)(
2
2
2222
191
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
,)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(222112
88112112)(
2
2
2222
201
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
,)cos()sin(
)cos(2112
)cos()sin(
)cos(222112
88112112)(
2
2
2222
211
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
.)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(222112
88112112)(
2
2
2222
221
A
BkCVL
A
BkAkkCCVL
L
LVLABCBkCAkCVu
When 0B and 0)1( CA , the solutions are
,)sinh()cosh()1(
112
)sinh()cosh()1(22112
88112112)(
2
1
12
1
1
2222231
AAcC
AckCVL
AAcC
AckAkkCCVL
L
LVLABCBkCAkCVu
242
Fig.7.6 (a-d): Solution 231u represents the bell-shaped 2sec h solitary traveling wave
solution for different values of and ,1,1,1,2,0,1 VLkCBA estranged by
infinite wings or infinite tails.
243
,)sinh()cosh()1(
))sinh()(cosh(112
)sinh()cosh()1(
))sinh()(cosh(22112
88112112)(
2
1
2
1
2222241
AAcC
AAAkCVL
AAcC
AAAkAkkCCVL
L
LVLABCBkCAkCVu
where 1c is an arbitrary constant.
When 0 BA and ,0)1( C the solution of (7.13) is
,)1(
1112
)1(
122112
88112112)(
2
2
2
2
2222251
cCkCVL
cCkAkkCCVL
L
LVLABCBkCAkCVu
where 2c is an arbitrary constant.
Inserting the solutions )(G of (1.56) in (7.20), the solutions are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
1112
)2/tanh(12
122112
88112112)(
222
1
2
222212
AC
kBkAkCVL
AC
kAkCBkAkCVL
L
LVLABCBkCAkCVu
,)2/coth(12
1112
)2/coth(12
122112
88112112)(
222
1
2
222222
AC
kBkAkCVL
AC
kAkCBkAkCVL
L
LVLABCBkCAkCVu
244
.))(sec)(tanh(12
1112
))(sec)(tanh(12
1
22112
88112112)(
222
1
2
2222
32
hiAC
kBkAkCVL
hiAC
k
AkCBkAkCVL
L
LVLABCBkCAkCVu
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(12
1112
)2/tan(12
122112
88112112)(
222
1
2
2222
122
AC
kBkAkCVL
AC
kAkCBkAkCVL
L
LVLABCBkCAkCVu
,)2/cot(12
1112
)2/cot(12
122112
88112112)(
222
1
2
2222132
AC
kBkAkCVL
AC
kAkCBkAkCVL
L
LVLABCBkCAkCVu
.))sec()(tan(12
1112
))sec()(tan(12
1
22112
88112112)(
222
1
2
2222
142
AC
kBkAkCVL
AC
k
AkCBkAkCVL
L
LVLABCBkCAkCVu
245
When 0 BA and 0)1( C , the solution of (7.13) is
,)1(
1112
)1(
122112
88112112)(
2
2
22
1
2
2
2222
252
cCkBkAkCVL
cCkAkCBkAkCVL
L
LVLABCBkCAkCVu
where 2c is an arbitrary constant.
Lastly, inserting the solutions )(G of (1.56) in (7.21) and simplifying, the solutions are:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1
14
443
))2/tanh(()1(2
1112
442)(
2
2
22
2
222
13
CC
ABCVL
CCVL
L
LVABCVLu
,))2/coth(()1(2
1
14
443
))2/coth(()1(2
1112
442)(
2
2
22
2
222
23
CC
ABCVL
CCVL
L
LVABCVLu
.)(sec)(tanh()1(2
1
14
443
)(sec)(tanh()1(2
1
112442
)(
2
2
22
2
222
33
hiCC
ABCVL
hiC
CVLL
LVABCVLu
The other exact solutions are omitted for the sake of simplicity.
246
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tan(()1(2
1
14
443
))2/tan(()1(2
1112
442)(
2
2
22
2
222
123
CC
ABCVL
CCVL
L
LVABCVLu
Fig.7.7 (a-d): Solution 123u represents the periodic traveling wave solution for
different values of and .1,1,2,2,1,2 VLkCBA
,))2/cot(()1(2
1
14
443
))2/cot(()1(2
1112
442)(
2
2
22
2
222
133
CC
ABCVL
CCVL
L
LVABCVLu
247
.)(sec)(tan()1(2
1
14
443
)(sec)(tan()1(2
1112
442)(
2
2
22
2
222
143
CC
ABCVL
CCVL
L
LVABCLVu
When 0)1( C and 0 BA , the solution of (7.13) is,
,)1(
1
)1(214
443
)1(
1
)1(2112
442)(
2
22
22
2
2
222
253
cCC
A
C
ABCVL
cCC
ACVL
L
LVABCVLu
where 2c is an arbitrary constant.
The other exact solutions of (7.13) are omitted here for convenience.
7.2.3. The Space-Time Fractional SRLW Equation
Consider the following space-time fractional SRLW equation [27] in the form
,10,02222 uDDuDuDuDuDuDuD xttxxtxt (7.22)
which arises in several physical applications including ion sound waves in plasma.
Using equations (1.6) and (1.52) that convert (7.22) in an ordinary differential equation of
integer order and after integrating twice yields,
,02
11
22222 CuVLuLVuVL (7.23)
where 1C is an integration constant. Considering the homogeneous balance between
u and 2u in (7.23), we obtain .22 mm i.e. .2m Therefore, the trial solution (1.54)
becomes,
.)()()()()(2
210
1
1
2
2
kkkku (7.24)
Proceeding as before, the following three solution sets are obtained:
Set 1.
,1122
2 CVL ,24212 21 kAACCkkCVL
,882412121212 222220
L
V
V
LABBCCkkACkAkkCLV
248
kkLLVV ,, , ,01 ,02 (7.25)
,22
328816162
332422222
33
1L
V
V
LLVCBABCABABCB
VLC
where k, L, V, A, B and C are arbitrary constants.
Set 2.
,882412121212 222220
L
V
V
LABBCCkkACkAkkCLV
,243322212 32223321 BCkCkACkkAAkkABkCBkLV
,22222212 243223422422 BCkABkCkACkkAAkkBBkkCLV
kkLLVV ,, ,02 ,01 (7.26)
,22
1328816162
332422222
33
1V
L
L
VLVCBABCABABCB
VLC
where k, L, V, A, B and C are arbitrary constants
Set 3.
,1122
2 CLV ,828 20
L
V
V
LBABCLV ,
)1(2
C
Ak
,81632816)1(4
3 4222222
22 ABABCBBCACBC
LV
,01 ,01 ,, LLVV (7.27)
,22
)64642568128128(33
2224222331
V
L
L
V
LVBABCACBABCBVLC
where V, L, A, B and C are arbitrary constants.
Substituting equations (7.25)- (7.27) in (7.24), The solution takes the form,
,)/(112
)/(24212
882412121212)(
22
2
222221
GGkCVL
GGkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
(7.28)
249
,)/()222
222(12)/(
243322212
882412121212)(
224
3223422421
3222332
222222
GGkBCkABkCk
ACkkAAkkBBkkCLVGGk
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
(7.29)
,)/()1(2
81632816)1(4
3
)/()1(2
112828)(
2
4222222
2
2
223
GGC
A
ABABCBBCACBC
LV
GGC
ACLV
L
V
V
LBABCLVu
(7.30)
where
;11
0
t
Vx
L k, L, V, A, B and C are arbitrary constants.
Inserting the solutions )(G of (1.56) in (7.28) and simplifying, the following solutions
are obtained:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(12
1112
)2/tanh(12
124212
882412121212)(
2
2
2
2222211
AC
kCVL
AC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)2/coth(12
1112
)2/coth(12
124212
882412121212)(
2
2
2
2222221
AC
kCVL
AC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
250
,)(sec)tanh(12
1112
)(sec)tanh(12
124212
882412121212)(
2
2
2
2222231
hiAC
kCVL
hiAC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)(csc)coth(12
1112
)(csc)coth(12
124212
882412121212)(
2
2
2
2222241
hAC
kCVL
hAC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)4/coth()4/tanh(214
1112
)4/coth()4/tanh(214
1
24212
882412121212)(
2
2
2
2222251
AC
kCVL
AC
k
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
1
24212
882412121212)(
222
2
22
2
2222261
BF
FHFA
CkCVL
BF
FHFA
Ck
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
251
,)sinh(
)cosh()(
12
1112
)sinh(
)cosh()(
12
1
24212
882412121212)(
222
2
22
2
2222271
BF
FHFA
CkCVL
BF
FHFA
Ck
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
where F and H are real constants.
,)2/cosh()2/sinh(
)2/cosh(2112
)2/cosh()2/sinh(
)2/cosh(224212
882412121212)(
2
2
2
2222281
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)2/sinh()2/cosh(
)2/sinh(2112
)2/sinh()2/cosh(
)2/sinh(224212
882412121212)(
2
2
2
2222291
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)cosh()sinh(
)cosh(2112
)cosh()sinh(
)cosh(224212
882412121212)(
2
2
2
22222101
iA
BkCVL
iA
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
252
.)sinh()cosh(
)sinh(2112
)sinh()cosh(
)sinh(224212
882412121212)(
2
2
2
22222111
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(12
1112
)2/tan(12
124212
882412121212)(
2
2
2
22222121
AC
kCVL
AC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)2/cot(12
1112
)2/cot(12
124212
882412121212)(
2
2
2
22222131
AC
kCVL
AC
kkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)sec()tan(12
1112
)sec()tan(12
1
24212
882412121212)(
2
2
2
22222141
AC
kCVL
AC
k
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
253
,)(csc)cot(12
1112
)(csc)cot(12
1
24212
882412121212)(
2
2
2
22222151
hAC
kCVL
hAC
k
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
882412121212)(
222
2
22
2
22222161
BF
FHFA
CkCVL
BF
FHFA
Ck
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
882412121212)(
222
2
22
2
22222171
BF
FHFA
CkCVL
BF
FHFA
Ck
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)sin(
)cos()(
12
1112
)sin(
)cos()(
12
1
24212
882412121212)(
222
2
22
2
22222181
BF
FHFA
CkCVL
BF
FHFA
Ck
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
where F and H are real constants such that .022 HF
254
,)2/cos()2/sin(
)2/cos(2112
)2/cos()2/sin(
)2/cos(224212
882412121212)(
2
2
2
22222191
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(224212
882412121212)(
2
2
2
22222201
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
,)cos()sin(
)cos(2112
)cos()sin(
)cos(224212
882412121212)(
2
2
2
22222211
A
BkCVL
A
BkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
.)2/sin()2/cos(
)2/sin(2112
)2/sin()2/cos(
)2/sin(2
24212
882412121212)(
2
2
2
22222221
A
BkCVL
A
Bk
kAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
255
When 0B and 0)1( CA , the solutions are
,)sinh()cosh()1(
112
)sinh()cosh()1(24212
882412121212)(
2
1
12
1
12
22222231
AAcC
AckCVL
AAcC
AckkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
25.0)a( 50.0)b(
75.0)c( 0.1)d(
Fig.7.8 (a-d): Solution 231u symbolizes the bell-shaped 2sec h solitary traveling wave
solution for different values of and ,1,1,1,2,0,1 VLkCBA alienated by
infinite wings or infinite tails.
256
,)sinh()cosh()1(
))sinh()(cosh(112
)sinh()cosh()1(
))sinh()(cosh(24212
882412121212)(
2
1
2
1
2
22222241
AAcC
AAAkCVL
AAcC
AAAkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
where 1c is an arbitrary constant.
When 0 BA and ,0)1( C the solution of (7.22) is
,)1(
1112
)1(
124212
882412121212)(
2
2
2
2
2
22222251
cCkCVL
cCkkAACCkkCVL
L
V
V
LABBCCkkACkAkkCLVu
where 2c is an arbitrary constant.
Inserting the solutions )(G of (1.56) in (7.29) and simplifying, we obtain the following
solutions:
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tanh(
12
1)2222
22(12)2/tanh(12
1
243322212
882412121212)(
2
24322
342242
1
3222332
2222212
AC
kBCkABkCkACkkA
AkkBBkkCLVAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
where
;11
0
VtLx
k, L, V, A, B and C are arbitrary constants.
257
,)2/coth(
12
1)2222
22(12)2/coth(12
1
243322212
882412121212)(
2
24322
342242
1
3222332
2222222
AC
kBCkABkCkACkkA
AkkBBkkCLVAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
.))(sec)(tanh(
12
1
)22222
2(12))(sec)(tanh(12
1
243322212
882412121212)(
2
24322342
242
1
3222332
2222232
hiAC
k
BCkABkCkACkkAAkkB
BkkCLVhiAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
The other exact solutions of (7.22) are omitted for convenience.
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,)2/tan(
12
1)2222
22(12)2/tan(12
1
243322212
882412121212)(
2
24322
342242
1
3222332
22222122
AC
kBCkABkCkACkkA
AkkBBkkCLVAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
258
25.0)a( 50.0)b(
75.0)c( 0.1)d(
Fig.7.9 (a-d): Solution 122u corresponds to the exact periodic traveling wave solution for
different values of and ,2,1,2 CBA .1,1,1 VLk
259
,)2/cot(
12
1)2222
22(12)2/cot(12
1
243322212
882412121212)(
2
24322
342242
1
3222332
22222132
AC
kBCkABkCkACkkA
AkkBBkkCLVAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
.))sec()(tan(
12
1
)222222
(12))sec()(tan(12
1
243322212
882412121212)(
2
243223422
42
1
3222332
22222142
AC
k
BCkABkCkACkkAAkkBBk
kCLVAC
k
BCkCkACkkAAkkABkCBkLV
L
V
V
LABBCCkkACkAkkCLVu
When 0 BA and 0)1( C , the solution of (7.22) is
,)1(
1)222
222(12)1(
1
)2433222(12
882412121212)(
2
2
24
322342242
1
2
3222332
22222252
cCkBCkABkCk
ACkkAAkkBBkkCLVcC
k
BCkCkACkkAAkkABkCBkLVL
V
V
L
ABBCCkkACkAkkCLVu
where 2c is an arbitrary constant.
Lastly, surrogating the solutions )(G of (1.56) in (7.30) and simplifying, we obtain the
following solutions:
260
When 0442 BBCA and 0)1( CA (or 0)1( CB ), the solutions are
,))2/tanh(()1(2
1
81632816)1(4
3
))2/tanh(()1(2
1112828)(
2
4222222
2
2
2213
C
ABABCBBCACBC
LV
CCLV
L
V
V
LBABCLVu
where
;11
0
VtLx
L, V, A, B and C are arbitrary constants.
,))2/coth(()1(2
181632816
)1(4
3
))2/coth(()1(2
1112828)(
2
4222222
2
2
2223
CABABCBBCACB
C
LV
CCLV
L
V
V
LBABCLVu
.)(sec)(tanh()1(2
1
81632816)1(4
3
)(sec)(tanh()1(2
1112828)(
2
4222222
2
2
2233
hiC
ABABCBBCACBC
LV
hiC
CLVL
V
V
LBABCLVu
Others families of exact solutions are omitted for the sake of simplicity.
When 0442 BBCA and 0)1( CA (or 0)1( CB ),
,))2/tan(()1(2
1
81632816)1(4
3
))2/tan(()1(2
1112828)(
2
4222222
2
2
22123
C
ABABCBBCACBC
LV
CCLV
L
V
V
LBABCLVu
261
25.0)a( 50.0)b(
75.0)c( 0.1)d(
Fig.7.10 (a-d): Solution 123u represents the exact singular periodic traveling wave
solution for different values of and .1,1,2,1,1 VLCBA
,))2/cot(()1(2
1
81632816)1(4
3
))2/cot(()1(2
1112828)(
2
4222222
2
2
22133
C
ABABCBBCACBC
LV
CCLV
L
V
V
LBABCLVu
262
,)(sec)(tan()1(2
1
81632816)1(4
3
)(sec)(tan()1(2
1112828)(
2
4222222
2
2
22143
C
ABABCBBCACBC
LV
CCLV
L
V
V
LBABCLVu
When 0)1( C and 0 BA , the solution of (7.22) is,
,)1(
1
)1(2
81632816)1(4
3
)1(
1
)1(2112828)(
2
2
4222222
2
2
2
22253
cCC
A
ABABCBBCACBC
LV
cCC
ACLV
L
V
V
LBABCLVu
where 2c is an arbitrary constant.
Discussion
The abundant new exact solutions for the time fractional partial differential equations
have been successfully obtained by applying the novel )/( GG -expansion method. The
nonlinear fractional complex transformation for is very important, which ensures that a
certain fractional partial differential equation can be converted into another ordinary
differential equation of integer order. The obtained solutions are more general with more
free parameters. Thus novel )/( GG -expansion method would be a trustworthy
mathematical tool for solving nonlinear evolution equations. Numerical results coupled
with graphical presentation for different values of reveals the complete reliability of
the proposed technique.
263
Chapter 8
Conclusion
264
In this thesis modified versions of )/( GG -expansion method have successfully applied
and implemented to investigate the nonlinear partial differential equations which
frequently arise in engineering sciences, mathematical physics and other scientific real
time application fields. Abundant exact traveling wave solutions including solitons,
periodic and rational solutions using symbolic computational software Maple 13 have
been constructed. The arbitrary constants in the obtained solutions imply that these
solutions have rich local structures. It has been observed that the proposed techniques are
quite useful, reliable, and efficient and can be extended for other nonlinear physical
problems. It is also observed that performance of modified versions is better than the
original scheme. Moreover, these modified algorithms give more solutions of nonlinear
partial differential equations. Computational work together with the graphical illustration
re-confirms the exactness of the proposed algorithms.
265
Chapter 9
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