incompressible navier stokes equation

15
preprint -- preprint -- preprint -- preprint -- preprint Kinetic derivation of a finite difference scheme for the incompressible Navier Stokes equation * Mapundi K. Banda Michael Junk Axel Klar Abstract In the present paper the low Mach number limit of kinetic equations is used to develop a discretization for the incompressible Navier-Stokes equation. The kinetic equation is discretized with a first and second order discretization in space. The discretized equation is then considered in the low Mach number limit. Using this limit a second order discretization for the convective part in the incompressible Navier Stokes equation is ob- tained. Numerical experiments are shown comparing different approaches. Keywords. kinetic equations, asymptotic analysis, low Mach number limit, second order upwind discretization, slope limiter, incompressible Navier-Stokes equation AMS subject classifications. 1 Introduction Kinetic equations or discrete velocity models of kinetic equations yield in the limit for small Knudsen or Mach numbers an approximation of macroscopic equations like the Euler or incompressible Navier Stokes equation. Discretiza- tions of kinetic models are often used in combination with the above limiting procedures to develop discretizations for the corresponding macroscopic limit equation. We consider first the Euler or hydrodynamic limit: As a first example of the above approach we mention the Kinetic Schemes. A simple kinetic relaxation model with a so called BGK operator is discretized. In the limit a scheme for the hyperbolic limit equation is obtained. There is a large amount of literature on the subject, examples can be found in [21, 20, 6, 7, 15]. A second example is given by the relaxation schemes developed in [14]. Based on a simplified kinetic model efficient second order upwind discretizations for the Euler equation are developed. For further examples and related schemes, see [3, 19, 12, 18]. * This work was supported by DAAD grant and by DFG grant Department of Mathematics, Technical University of Darmstadt, 64289 Darmstadt, Ger- many. Department of Mathematics, University of Kaiserslautern, 67665 Kaiserslautern, Ger- many. 1

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Page 1: incompressible Navier Stokes equation

preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint -- preprint --

Kinetic derivation of a finite difference scheme for the

incompressible Navier Stokes equation ∗

Mapundi K. Banda† Michael Junk‡ Axel Klar†

Abstract

In the present paper the low Mach number limit of kinetic equationsis used to develop a discretization for the incompressible Navier-Stokesequation. The kinetic equation is discretized with a first and second orderdiscretization in space. The discretized equation is then considered in thelow Mach number limit. Using this limit a second order discretizationfor the convective part in the incompressible Navier Stokes equation is ob-tained. Numerical experiments are shown comparing different approaches.

Keywords. kinetic equations, asymptotic analysis, low Mach number limit,second order upwind discretization, slope limiter, incompressible Navier-StokesequationAMS subject classifications.

1 Introduction

Kinetic equations or discrete velocity models of kinetic equations yield in thelimit for small Knudsen or Mach numbers an approximation of macroscopicequations like the Euler or incompressible Navier Stokes equation. Discretiza-tions of kinetic models are often used in combination with the above limitingprocedures to develop discretizations for the corresponding macroscopic limitequation.We consider first the Euler or hydrodynamic limit: As a first example of theabove approach we mention the Kinetic Schemes. A simple kinetic relaxationmodel with a so called BGK operator is discretized. In the limit a scheme forthe hyperbolic limit equation is obtained. There is a large amount of literatureon the subject, examples can be found in [21, 20, 6, 7, 15].A second example is given by the relaxation schemes developed in [14]. Basedon a simplified kinetic model efficient second order upwind discretizations forthe Euler equation are developed. For further examples and related schemes,see [3, 19, 12, 18].

∗This work was supported by DAAD grant and by DFG grant†Department of Mathematics, Technical University of Darmstadt, 64289 Darmstadt, Ger-

many.‡Department of Mathematics, University of Kaiserslautern, 67665 Kaiserslautern, Ger-

many.

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As already mentioned, another scaling - the diffusive scaling - gives in thelimit the incompressible Navier Stokes equation. Again kinetic models - usuallybased on a small number of velocities - are discretized and investigated in theincompressible Navier Stokes limit.A well known example are the Lattice-Boltzmann methods, see [9, 4, 11, 8].Also relaxation schemes for diffusive limits have been developed for example in[13, 17]. See also [18, 1] for related schemes for the limit equations.In the present paper we start by recalling the diffusive scaling of kinetic equa-tions, leading to the incompressible Navier Stokes equation. Then, a naturaldiscretization of the kinetic equation is used to obtain in the limit a secondorder slope limiting procedure for the convective term of the Navier Stokesequation. For the slope limiting procedure the behavior of the solution in allspatial directions is important not only along the values of the solution alongthe coordinate axis.The paper is organized as follows: Section 2 contains a short description ofthe results of the asymptotic analysis leading from kinetic equations to theincompressible Navier Stokes equation. In section 3 the asymptotic procedure isperformed for the discretized kinetic equations and a general limit discretizationfor the incompressible Navier Stokes equation is derived. In 4 we concentrate onthe derivation of the discretization of the convective part. A first and secondorder upwind discretization for the limit equation is derived. Whereas thefirst order discretization is standard, the second order discretization includes amultidimensional slope limiting procedure.

2 Kinetic Equations and the Incompressible Navier

Stokes Equation

The incompressible Navier Stokes equation

∂tu+ u · ∇u+ ∇xp = µ∆xu, div xu = 0 (2.1)

is a reasonable model to describe the large scale and long time behavior of aslowly flowing isothermal gas. We will use the fact that (2.1) can be formallyobtained as scaling limit of a Boltzmann type kinetic equation

∂tf + v · ∇xf = J(f). (2.2)

Here, f = f(x, v, t) is the phase space density of the gas atoms which weconsider, for simplicity, in the two dimensional case x = (x1, x2) ∈ R

2, v =(v1, v2) ∈ R

2. We will not specify the complete structure of the collision opera-tor J(f). Only those properties which are important in the Navier Stokes limitwill be listed below.Using the diffusive space-time scaling x 7→ x/ε, and t 7→ t/ε2, the restriction tolarge scale and long time behavior is incorporated. We find the scaled kineticequation

∂tf +1

εv · ∇xf =

1

ε2J(f). (2.3)

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The assumption of very slow, isothermal flows which exhibit only small densityvariations is then taken care of by assuming that f is only a small perturbationof the Maxwellian velocity distribution M

M(v) =1

2πexp

(

−|v|2

2

)

, v ∈ R2

which corresponds to the constant state: density one, velocity zero, and tem-perature one. Our precise assumption on the structure of f is

f = M(1 + εg), g = g0 + εg1 + ε2g2 + . . . . (2.4)

The scaled equation (2.3) together with (2.4) is the standard perturbation pro-cedure to obtain (2.1) as limiting problem (see [2, 5, 22]). In the next section,we demonstrate this procedure in a slightly more general situation where (2.3)is modified by adding a diffusive term Dh(v)f and replacing ∇x with an ap-proximation ∇h

x.Let us now list some properties of J which will be needed for the analysis:if (2.4) is inserted into (2.3) we need a Taylor expansion of J(M + εMg) tocompare terms of equal order in ε. We have

1

MJ(M + εMg) = εLg +

1

2ε2Q(g, g) + ε3R(g) (2.5)

where L involves the first and Q the second Frechet derivative of J at the pointM (see [2] for details). The exact structure of the remainder R is not relevantin the limit. Note that the zero order term in (2.5) drops out because of theassumed equilibrium condition

J(M) = 0. (2.6)

Another important assumption is that the collision invariants of J are the func-tions 1, v1, v2 (in isothermal flows |v|2 is not a collision invariant), which meansin terms of the weighted L

2 scalar product 〈g, h〉 =∫

R2 ghM dv

1

MJ(f), ψ

= 0, ψ ∈ {1, v1, v2}. (2.7)

Note that (2.7) implies together with (2.5) that also

〈Lg, ψ〉 = 〈Q(g, g), ψ〉 = 〈R(g), ψ〉 = 0 (2.8)

for all collision invariants ψ. Important assumptions on the operator L are

1) L is selfadjoint with respect to 〈·, ·〉 and 〈Lh, h〉 ≤ 0.

2) L satisfies a Fredholm alternative with a three dimensional kernel spannedby the collision invariants (we denote the pseudo inverse of L by L†, i.e.L†L is the orthogonal projection onto (kerL)⊥).

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Additionally, with µ, λ > 0

L†(vkvl), vi

= 0,⟨

L†(vkvl), vivj

= −λδklδij − µ(δikδjl + δilδjk), (2.9)

which would be a consequence of invariance of J under certain coordinate trans-formations in the velocity space as well as L being self adjoint and semi definite.Finally, we need a property of Q which is a direct consequence of the relation

Q(h, h) = −Lh2 for h = α+ β · v (2.10)

(see [2] for the derivation). Using the fact that 1, v1, v2 are in the kernel of Land that L†L is the projection onto (kerL)⊥, we conclude

−L†Q(h, h) = βiβjL†L(vivj) = βiβj(vivj − δij). (2.11)

The projection has been calculated with the usual Schmidt procedure which re-quires the scalar products 〈1, vivj〉 and 〈vk, vivj〉. Such moments of the standardMaxwellian will be frequently used later and we list them here for convenience

〈1, 1〉 = 1, 〈1, vi〉 = 0, 〈vi, vj〉 = δij

〈vivj, vk〉 = 1, 〈vivj , vkvl〉 = δijδkl + δikδjl + δjkδil.(2.12)

3 The discretized kinetic equation and derivation of

macroscopic discretization

We start with the kinetic equation (2.2) which is discretized using the methodof lines

∂tf + v · ∇hxf −Dh(v)f = J(f).

In this section, we only assume that ∇hx = (∂h

x1, ∂h

x2) and Dh(v) are linear oper-ators, that ∇h

x is independent of v, and that the components of ∇hx commute. In

the next section we choose ∂hxi

as central difference approximations and Dh(v)as numerical viscosity term.Introducing the diffusive scaling as in the previous section and rescaling Dh(v)faccording to ε2Dh(v)f , we find

∂tf +1

εv · ∇h

xf −Dh(v)f =1

ε2J(f).

With the expansion (2.4) and (2.5), we then get

∂tg +1

εv · ∇h

xg −Dh(v)g =1

ε2Lg +

1

2εQ(g, g) +R(g).

and the regular expansion g = g0 + εg1 + ε2g2 + . . . leads to

∂tg +1

εv · ∇h

xg −Dh(v)g

=1

ε2Lg0 +

1

ε

(

Lg1 + 12Q(g0, g0)

)

+(

Lg2 +Q(g0, g1) +R(g0))

+ O(ε) (3.1)

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In lowest order ε−2 we immediately find Lg0 = 0 so that g0 ∈ kerL, i.e.

g0(v) = ρ+ u · v, ρ ∈ R, u ∈ R2 (3.2)

with parameters ρ, u which are yet undetermined. In order ε−1, we have

v · ∇hxg0 = Lg1 + 1

2Q(g0, g0) (3.3)

and with (2.8) we conclude⟨

v · ∇hxg0, 1

= 0,⟨

v · ∇hxg0, vi

= 0. (3.4)

Using (3.2), the first condition can be reformulated

0 = ∂hxi〈g0, vi〉 = ∂h

xi〈ρ+ vjuj , vi〉

= 〈1, vi〉 ∂hxiρ+ 〈vj, vi〉 ∂

hxiuj = ∂h

xiui = : div h

xu

where we have used moment relations from (2.12). Similarly, we find

0 = ∂hxj

〈vjg0, vi〉 = 〈vj, vi〉 ∂hxiρ+ 〈vjvk, vi〉 ∂

hxiuk = ∂h

xiρ

so that (3.4) impliesdiv h

xu = 0, ∇hxρ = 0 (3.5)

which has to be satisfied by the parameters ρ, u in (3.2). Applying L† to (3.3),we obtain the projection of g1 onto (kerL)⊥, so that with additional parametersρ(1), u(1)

g1 = L†(

v · ∇hxg0 −

12Q(g0, g0)

)

+ ρ(1) + u(1) · v.

Using (3.5), we can calculate

v · ∇hxg0 = vi∂

hxi

(ρ+ vjuj) = vivj∂hxiuj

and hence L†v · ∇hxg0 = (∂h

xiuj)L

†(vivj). The expression −L†Q(g0, g0) can besimplified with (2.11), so that

g1 = (∂hxiuj)L

†(vivj) + 12uiuj(vivj − δij) + ρ(1) + u

(1)j vj. (3.6)

Going back to (3.1) and collecting terms of order ε0, we find

∂tg0 + v · ∇hxg1 −Dh(v)g0 = Lg2 +Q(g0, g1) +R(g0). (3.7)

Again, property (2.8) yields conditions on the undetermined parameters in g0

and g1. Integrating (3.7) and observing that 〈g1, vi〉 = u(1)i because of (2.9) and

(2.12), we get a divergence condition on u(1)

∂tρ+ div hxu

(1) = 〈Dh(v)g0, 1〉 .

Integration of v · ∇hxg1 after multiplication with ψ = vj yields with the help of

(2.9) and (2.12)

∂hxi〈vig1, vj〉 = (∂h

xi∂h

xkul)(−λδklδij − µ(δikδjl + δilδjk))

+ 12∂

hxi

(uluk)(δikδjl + δilδjk) + ∂hxjρ(1)

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so that the vj weighted integral of (3.7) leads to

∂tuj + ∂hxi

(uiuj) − 〈Dh(v)g0, vj〉 + ∂hxjρ(1)

= λ∂hxj

(∂hxkuk) + µ∂h

xk(∂h

xjuk) + µ∂h

xi∂h

xiuj .

Taking into account that ∂hx1

and ∂hx2

commute, relation (3.5) implies thatλ∂h

xj(∂h

xkuk) = µ∂h

xk(∂h

xjuk) = 0. Introducing the discretized Laplacian ∆h

x =

∂hxi∂h

xi, we have the final result

∂tuj + ∂hxi

(uiuj) − 〈Dh(v)g0, vj〉 + ∂hxjρ(1) = µ∆h

xuj , div hxu = 0. (3.8)

Note that (3.8) reduces to the incompressible Navier Stokes equation (2.1) if wechoose ∇h

x = ∇x and Dh(v) = 0. Obviously, ρ(1) takes the role of the pressureand ∂h

xi(uiuj)−〈Dh(v)g0, vj〉 gives a discretization of the convective terms ones

the numerical viscosity is fixed.

4 First and second order upwind schemes

To find expressions for ∇hx and the numerical viscosity Dh(v) we consider the

linear transport part of the kinetic equation in two dimensions:

v · ∇xf = v1∂x1f + v2∂x2f. (4.1)

A first order discretization is given by

v1∂hx1f + v2∂

hx2f −

c1h

2∂2,h

x1f −

c2h

2∂2,h

x2f (4.2)

with positive constants c1, c2 and

(∂hx1f)ij =

1

2h(fi+1j − fi−1j), (∂2,h

x1f)ij =

1

h2(fi+1j − 2fij + fi−1j),

(∂hx2f)ij =

1

2h(fij+1 − fij−1), (∂2,h

x2f)ij =

1

h2(fij+1 − 2fij + fij−1).

The constants are chosen later according to the macroscopic flow situation underconsideration. In view of (4.2), we define

Dh(v)f =

(

c1h

2∂2,h

x1f + c2

h

2∂2,h

x2f

)

and obtain

Dh(v)g0 = c1∂2,hx1ρh

2+ c2∂

2,hx2ρh

2+ c1∂

2,hx1uihvi

2+ c2∂

2,hx2uihvi

2

which yields with (2.12) the required expressions in (3.8)

〈Dh(v)g0, v〉 =h

2

(

c1∂2,hx1 u+ c2∂

2,hx2 u

)

.

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PSfrag replacements

S0

S1

S2

0

0y

y

y

x

y − x

y − x

Figure 1: Piecewise linear definition of φ(x, y) in the sets S0, S1, S2

A second order discretization of (4.1) is obtained by slope limiting

(v · ∇hxf)ij−

[c1(i, j)

2h

(

(1 − ϕi+ 12j)∆i+ 1

2jf − (1 − ϕi− 1

2j)∆i− 1

2jf

)

+c2(i, j)

2h

(

(1 − ϕij+ 12)∆ij+ 1

2f − (1 − ϕij− 1

2)∆ij− 1

2f)]

(4.3)

where ∇hx are again central differences, the f increments are defined by

∆i+ 12jf = fi+1j − fij, ∆ij+ 1

2f = fij+1 − fij,

and

ϕi+ 12j = ϕ(ri+ 1

2j), ri+ 1

2j = ∆i− 1

2jf/∆i+ 1

2jf

ϕij+ 12

= ϕ(rij+ 12), rij+ 1

2= ∆ij− 1

2f/∆ij+ 1

2f,

with ϕ(r) = max{0,min{r, 1}} being the minmod limiter. Using the definitionof ϕ, one can write expressions like (1 − ϕi+ 1

2j)∆i+ 1

2jf as φ(∆i− 1

2jf,∆i+ 1

2jf)

where φ is a continuous, piecewise linear function on R2 defined according to

figure 1. Extracting the viscosity term in (4.3), we get

Dh(v)fij =c1(i, j)

2h

(

φ(∆i− 12jf,∆i+ 1

2jf) − φ(∆i− 3

2jf,∆i− 1

2jf)

)

+c2(i, j)

2h

(

φ(∆ij− 12f,∆ij+ 1

2f) − φ(∆ij− 3

2f,∆ij− 1

2f)

)]

Now, the task to calculate 〈Dh(v)g0, vj〉 is more involved than in the first ordercase. We start with the observation that

∆i+ 12jg0 = (∆i+ 1

2ju) · v

because ρ satisfies ∇hxρ = 0. Hence, a typical term appearing in 〈Dh(v)g0, v〉

has the form〈φ(δ1 · v, δ2 · v), v〉 δ1, δ2 ∈ R

2. (4.4)

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Introducing the linear map

T =

(

δ11 δ12δ21 δ22

)

we can rewrite (4.4) as 〈φ(Tv), v〉. Note that φ is linear in the convex setsS0, S1, S2 (see figure 1). With the unit vectors e1 = (1, 0), e2 = (0, 1) and

S(a, b) = S+(a, b) ∪ S−(a, b), S± = {±(λ1a+ λ2b) : λ1, λ2 ≥ 0},

we can describe these sets as

S0 = S(e1, e1 + e2), S1 = (e1 + e2, e2), S2 = S(e2,−e1).

Assuming that T is invertible, we conclude that φ ◦ T is linear on the setsSi = T−1Si. Since S(a, b) = cS(a, b) for all c 6= 0, we have Si = T (Si) where

T = (detT )T−1 =

(

δ22 −δ12−δ21 δ11

)

=(

−δ⊥2 δ⊥1)

.

Hence,

S0 = S(−δ⊥2 , δ⊥1 − δ⊥2 ), S1 = S(δ⊥1 − δ⊥2 , δ

⊥1 ), S2 = S(δ⊥1 , δ

⊥2 ).

Taking into account that φ vanishes on S0, we find

〈φ(Tv), v〉 =

S1

(δ2 · v − δ1 · v)vM(v) dv +

S2

(δ2 · v)vM(v) dv

or with the help of the matrix valued function

I(a, b) =

S(a,b)v ⊗ vM(v) dv

that

〈φ(Tv), v〉 = I(δ⊥1 − δ⊥2 , δ⊥1 )(δ2 − δ1) + I(δ⊥1 , δ

⊥2 )δ2 = : L(δ1, δ2).

Hence, the numerical viscosity for the second order discretization has the form

〈Dh(v)g0, v〉ij =c1(i, j)

2h

(

L(∆i− 12ju,∆i+ 1

2ju) − L(∆i− 3

2ju,∆i− 1

2ju)

)

+c2(i, j)

2h

(

L(∆ij− 12u,∆ij+ 1

2u) − L(∆ij− 3

2u,∆ij− 1

2u)

)]

We conclude by giving an explicit formula for the function I. First, we notethat, using the symmetry of M(v) and v ⊗ v

I(a, b) = 2

S+(a,b)v ⊗ vM(v) dv.

Using that S+(a, b) is a cone with some opening angle 0 < β < π around the

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PSfrag replacements

a

b v1

v2

α

βS+(a, b)

Figure 2: Angles α, β characterizing the cone S+(a, b)

ray in direction α (see figure 2), we go over to polar coordinates and find

I(a, b) = 2

∫ α+β/2

α−β/2

(

cos2 ψ sinψ cosψsinψ cosψ sin2 ψ

)

∫ ∞

0

r2

2πe−

r2

2 r dr.

After some straight forward calculations we get

I(a, b) =1

π

(

δ + sin δ

(

cos(2α) sin(2α)sin(2α) − cos(2α)

))

.

In the case where T is not invertible, one can either slightly modify the rowvectors δ1, δ2 in order to obtain an invertible mapping (note that 〈φ(Tv), v〉 iscontinuous in T ), or one can use the relation

〈φ(Tv), vj〉 = φ(Tej). (4.5)

To prove (4.5), let us consider the case δ2 = γδ1. Then, Tv = δ1 · v(

)

andφ(Tv) = (δ1 · v)φ(1, γ). Now, 〈δ1 · v, vj〉 = δ1 · ej so that (4.5) follows. The caseδ1 = γδ2 can be treated similarly.

5 Numerical results

We investigate the above first and second order discretizations of the convectiveterm numerically for the following stationary equation and compare them withthe second order scheme described in [18]. The viscous term ε∆u is treated bystraightforward second order central differences.

∇x(u⊗ u) − ε∆u = 0 + boundary conditions

To test our scheme for pure convection we use test examples for the stationarycase as presented in [10].The first example is pure convection of a Step Profile, i.e. the following flowsituation is considered: Consider (x1, x2) in [0, 1]2. The domain of computationis divided into two subdomains which give a step profile as sketched below.

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PSfrag replacements

(0,1)

(0,0)

(1,1)

(1,0)

x1

x2

x1

x2

|u| = 2

|u| = 1

(1 − tan θ)/2

(1 − tan θ)/2

u = |u|

(

cos θsin θ

)

θ

00.2

0.40.6

0.81

0

0.2

0.4

0.6

0.8

11

1.2

1.4

1.6

1.8

2

3D Illustration of Step Profile

PSfrag replacements

(0,1)

(0,0)

(1,1)

(1,0)

x1x2

x1

x2

|u| = 2

|u| = 1

(1 − tan θ)/2

u = |u|

(

cos θsin θ

)

θ

Boundary values are chosen according to the respective domain. The solutiondomain is discretized using a 41 × 41 regular mesh for different flow angles θ.We may choose c1 and c2 constant proportional to the maximal flow velocity:

c1 = maxij{|2uij |}, c2 = maxij{|2vij |}.

Alternatively the local flow velocity can be used:

c1(i, j) = max{|2ui+1j |, |2uij |}, c2(i, j) = max{|2vij+1|, |2vij |}

In our numerical tests the local flow velocity is used.The resulting nonlinear system is solved by a GMRES-based solver describedand implemented by Kelley [16].The results are plotted in the following figures. They show the computed profileat the line x1 = 1

2 for both the velocity components u1 and u2. In the figures wemake a comparison of the first order upwind method, the second order approachby Kurganov and Tadmor [18] and the kinetic second order approach developedhere. We always use the local flow velocity to determine c1 and c2.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Step Profile, θ = π/4,ε = 0

y

u

exact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Step Profile, θ = π/4,ε = 0

y

v

exact Upwind KT Kinetic

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7Pure convection of a Step Profile, θ = 35°,ε = 0

y

uexact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.5

0.6

0.7

0.8

0.9

1

1.1

1.2Pure convection of a Step Profile, θ = 35°,ε = 0

y

v

exact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.8

1

1.2

1.4

1.6

1.8

2Pure convection of a Step Profile, θ = 25°,ε = 0

y

u

exact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.4

0.5

0.6

0.7

0.8

0.9Pure convection of a Step Profile, θ = 25°,ε = 0

y

v

exact Upwind KT Kinetic

The second example is pure convection of a box-shaped profile:We consider a box-shaped profile as shown in the figure below. As in theprevious example we compare approximations of the profile across a verticalplane in the middle of the solution domain. We compare the different schemesusing a uniform 41 × 41 mesh.

PSfrag replacements

(0,1)

(0,0)

(1,1)

(1,0)

x1

x2

x1

x2

|u| = 2

|u| = 1

|u| = 1y∗

y∗

y∗y∗

45◦

u1

u2

00.2

0.40.6

0.81

0

0.5

11

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

3D Illustration of Box Profile

PSfrag replacements

(0,1)

(0,0)

(1,1)

(1,0)

x1x2

x1

x2

|u| = 2

|u| = 1

y∗

45◦

u1

u2

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Box Profile, θ = π/4,ε = 0,y* = 0.15

y

uexact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Box Profile, θ = π/4,ε = 0, y* = 0.15

y

v

exact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Box Profile, θ = π/4,ε = 0, y* = 0.2

y

u

exact Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Pure convection of a Box Profile, θ = π/4,ε = 0, y* = 0.2

y

v

exact Upwind KT Kinetic

The figures show that in the cases considered here the results are comparableto those obtained by the Kurganov-Tadmor approach.Further, the convection-diffusion equation for the step-profile is considered. Wechoose ε = 0.001. Just like in the previous examples we took a uniform 41× 41mesh.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Convection−Diffusion of a Step Profile, θ = π/4,ε = 0.001

y

u

Upwind KT Kinetic

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Convection−Diffusion of a Step Profile, θ = π/4,ε = 0.001

y

v

Upwind KT Kinetic

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Convection−Diffusion of a Step Profile, θ = π/4

y

uKinetic ε = 0 Kinetic ε = 0.001

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6Convection−Diffusion of a Step Profile, θ = π/4

y

v

Kinetic ε = 0 Kinetic ε = 0.001

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4Convection−Diffusion of a Box Profile, θ = π/4

y

u

Kinetic ε = 0 Kinetic ε = 0.001

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.7

0.8

0.9

1

1.1

1.2

1.3

1.4Convection−Diffusion of a Box Profile, θ = π/4

y

v

Kinetic ε = 0 Kinetic ε = 0.001

Conclusion

Starting from special discretizations of the Boltzmann equation we have ob-tained corresponding discretizations of the incompressible Navier Stokes equa-tion in the diffusive, low Mach number limit. In particular, a second order slopelimiting approach on the kinetic level gives rise to a limiter for the nonlinearterm in the Navier Stokes equation which exhibits an intersting structure. Fromthe simple numerical tests one can conclude that the new scheme yields resultswhich are comparable to those obtained by other second order methods. Atest of the new limiter in more complicated flow situations with strongly locallyvarying velocity fields is in preparation.

References

[1] Kurganov A. and D. Levy. A third-order semi-discrete central scheme forconservation laws and convection diffusion equations. preprint.

[2] C. Bardos, F. Golse, and D. Levermore. Fluid dynamic limits of kineticequations: Formal derivations. J. Stat. Phys., 63:323–344, 1991.

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[3] R.E. Caflisch, S. Jin, and G. Russo. Uniformly accurate schemes for hy-perbolic systems with relaxation. SIAM J. Num. Anal., 34:246–281, 1997.

[4] S. Chen and G.D. Doolen. Lattice Boltzmann method for fluid flows. Ann.Rev. Fluid Mech., 30:329–364, 1998.

[5] A. De Masi, R. Esposito, and J.L. Lebowitz. Incompressible Navier Stokesand Euler limits of the Boltzmann equation. CPAM, 42:1189, 1989.

[6] S.M. Deshpande. A second order accurate kinetic theory based method forinviscid compressible flows. Tec. Paper, NASA-Langley Research Center,2613, 1986.

[7] S.M. Deshpande. Kinetic Flux Splitting Schemes. Computational FluidDynamics Review 1995 : A state-of-the-art reference to the latest develop-ments in CFD, (eds.) M.M. Hafez and K. Oshima, 1995.

[8] B. Elton, C. Levermore, and G. Rodrigue. Convergence of convective dif-fusive lattice Boltzmann methods. SIAM J. Numer. Anal., 32:1327–1354,1995.

[9] U. Frisch, D. d’Humieres, B. Hasslacher, P. Lallemand, Y. Pomeau, andJ.P. Rivet. Lattice gas hydrodynamics in two and three dimensions. Com-plex Systems, 1:649–707, 1987.

[10] P.H. Gaskell and A.K.C. Lau. Curvature-compensated convective trans-port: Smart, a new boundedness-preserving transport algorithm. Int. J.Num. Meth. in Fluids, 8:617–641, 1988.

[11] T. Inamuro, M. Yoshino, and F. Ogino. Accuracy of the lattice Boltzmannmethod for small Knudsen number with finite Reynolds number. Phys.Fluids, 9:3535–3542, 1997.

[12] S. Jin and D. Levermore. Numerical schemes for hyperbolic conservationlaws with stiff relaxation terms. J. Comp. Phys., 126:449, 1996.

[13] S. Jin, L. Pareschi, and G. Toscani. Diffusive relaxation schemes fordiscrete-velocity kinetic equations. SIAM J. Num. Anal., 35:2405–2439,1998.

[14] S. Jin and Z. Xin. The relaxation schemes for systems of conservationlaws in arbitrary space dimensions. Comm. Pure Appl. Math., 48:235–276,1995.

[15] M. Junk. Kinetic schemes in the case of low Mach numbers. J. Comp.Phys., 151:947–968, 1999.

[16] C.T. Kelley. Iterative methods for linear and nonlinear equations. SIAM,Philadelphia, 1995.

[17] A. Klar. Relaxation schemes for a Lattice Boltzmann type discrete velocitymodel and numerical Navier Stokes limit. J. Comp. Phys., 148:1–17, 1999.

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[18] A. Kurganov and E. Tadmor. New high-resolution central schemes fornonlinear conservation laws and convection-diffusion equations. J. Comp.Phys., 160:241–282, 2000.

[19] H. Liu and G. Warnecke. Convergence rates for relaxation schemes ap-proximating conservation laws. preprint.

[20] B. Perthame. Boltzmann type schemes for gas dynamics and the entropyproperty. SIAM J. Numer. Anal., 27:1405–1421, 1990.

[21] B. Perthame. Second-order Boltzmann schemes for compressible Eulerequations in one and two space dimensions. SIAM J. Numer. Anal., 29:1,1992.

[22] Y. Sone. Asymptotic theory of a steady flow of a rarefied gas past bodiesfor small Knudsen numbers. In R. Gatignol and Soubbaramayer, editors,Advances in Kinetic Theory and Continuum Mechanics, Proceedings of aSymposium Held in Honour of Henri Cabannes (Paris), Springer, pages19–31, 1990.

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