cfx project

`

[Project: High speed Train

nose analysis]

[MAE]

[505] [Computer Modeling of Complex Thermal-Fluid System]

[ 12th May 2011]

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Contents 1 Introduction of High Speed Train ............................................................................................... 3

1.1 Definition ........................................................................................................................... 3

1.2 History ............................................................................................................................... 3

1.3 Advantages ........................................................................................................................ 5

1.4 Objectives of the project ..................................................................................................... 5

1.5 Scope of work .................................................................................................................... 6

1.6 Computational fluid dynamics V/S Wind tunnel ................................................................. 6

1.7 Analysis of High Speed Train Nose using Different Geometry.............................................. 8

1.7.1 Input Parameters ...................................................................................................... 13

1.8 Results ............................................................................................................................. 14

1.8.1 Top view configurations ........................................................................................... 14

1.8.2 Side View Configuration .......................................................................................... 15

1.9 Appendix .......................................................................................................................... 22

1.9.1 CCL for Case A .......................................................................................................... 22

1.9.2 CCL for Case B........................................................................................................... 25

1.9.3 CCL for Case C........................................................................................................... 28

1.9.4 CCL for Case D .......................................................................................................... 32

1.9.5 Convergence Residual Plots ...................................................................................... 36

1.9.6 Dimensions for the Model ........................................................................................ 37

1.9.7 References : ............................................................................................................. 41

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1 Introduction of High Speed Train

1.1 Definition

The UIC (International Union of Railways) defines high speed rail as services which

regularly operate at or above 250 km/h on new tracks, or 200 km/h on existing tracks.

A number of characteristics are common to most high speed rail systems. Curve

radius will often be the ultimate limiting factor in a train's speed, with passenger

discomfort often more important than the danger of derailment. Magnetic levitation

trains fall under the category of high speed rail due to their association with track

oriented vehicles; however their inability to operate on conventional railroads often

leads to their classification in a separate category.

1.2 History

The first high speed train in the world was opened by the Japan, between Tokyo and

Osaka, in time for 1964 Olympics. Ref. by High speed train of Japan and France.

Figure 1.1

Figure 1 a) JR East Shinkansen trains (Japan) and b) TGV (France)

The maximum speed of first Shinkansen (new trunk line) service was 210 km/h (131

mph) and took four hours between the two cities. Later on improving the vehicles,

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with maximum speed of 277 km/h (172 mph) took less than three hours. Within

several years, the digit of speed reached to 443 km/h (275 mph) for test runs in 1996

and finally up to a world record 581 km/h (361 mph) for maglev (magnetic levitation)

train in 2003. With a brief view on other high speed line, some countries will be

found in the competition. The table mentioned below introduces the most friendly

high speed rail countries and their speed of rail.

Records in Trial Runs

From the beginning of high speed train, the continuous modification, improvement

and aid of latest technology reaches the speed to 581 km/h (Japan MLX01). The

survey for land speed record for railed vehicles focus on digit of speed of different

nations. Ref. by High speed Rail from Wikipedia.

Table 1 - Speed line of nations

Year Nation Speed records (km/h) Remarks

1963 Japan 256 1st nation to develop HSR

1965 West Germany 200 2nd nation to develop HSR

1967 France 318 3rd nation to develop HSR

1974 France 430 High speed monorail train

1979 Japan 319

1981 France 380

1988 Italy 319 4th nation to develop HSR

1993 Japan 425

1993 Germany 450

1994 Japan 431

1996 Japan 446

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2002 Spain 362 5th nation to develop HSR

2002 China 321 6th nation to develop HSR

2003 Japan 581 Current world record holder

2004 South Korea 352.4 7th nation to develop HSR

2007 France 574.8

2008 China 394.3

1.3 Advantages

1. Due to infrastructure design in many nations, highway and air travel systems

are constrained. It cannot expand and in many cases are overloaded. High

speed rail has the potential for high capacity on its fixed corridors and has the

potential relieve congestion on other transit systems.

2. High speed trains are also considered more energy efficient or equivalent to

other modes of transit per passenger mile.

3. In terms of possible passenger capacity, high speed trains can also reduce the

amount of land used per passenger when compared to cars on roads.

4. Well established high speed rail systems are more environmentally friendly

than air or road travel. This is due to lower energy consumption per passenger

kilometer.

5. Rail travel has considerably less weather dependency than does air travel.

1.4 Objectives of the project

On the increasing demand of high speed transportation vehicle it is necessary to have

a better design and good service that can be achieved only by continuous

improvement of high speed train nose. The purpose of this project is to address the

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need for an Aerodynamic nose shape which will help in using various types of

geometries used as the High speed train1, while running on a normal terrain. This is

not enough to specify whole domain but it is only the problem on which one can keep

idea to invent a new horizon.

The ultimate goal is to optimize the shape of the nose by providing the smooth and

gradual flow of air around the nose of the train. 3 D models are developed using CAD

tool with proper surfacing.

1.5 Scope of work

Decide the way to obtain different geometry based on mathematical curves.

Study of aerodynamics around streamlines.

Study of CFD and its method for flow analysis.

Comparison of the results.

1.6 Computational fluid dynamics V/S Wind tunnel

The wind tunnel has played a leading role in aerodynamic performance analysis since

the first days of powered flight when the Wright brothers used a wind tunnel to

evaluate the lift and drag of the airfoil profiles. A wind tunnel simulates the

movement of an object (e.g. an aircraft, a train nose or a car) through air by placing a

stationary scale model of the object within a duct and either blowing or sucking air

through the duct. Mounting the model on a force balance allows measurement of

forces, such as drag and lift or downforce, as the air interacts with the scale model.

Later, wind tunnel testing was applied to automobiles to determine ways to reduce the

power required to move the vehicles on a roadways at a given speed. Ref. from

Wikipedia, NASA wind tunnel.

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Figure 2 (NASA wind tunnel with the model of plane)

Air is blown or sucked through a duct equipped with a viewing port and instruments

where models and geometrical shapes are mounted for testing. Typically the air is

moved through the tunnel using a series of fans. For large wind tunnels a single large

fan is not practical so an array of multiple fans is used in parallel to provide sufficient

airflow.

Wind tunnel classification

a) Low speed wind tunnel: Low speed wind tunnels are used for operations at very low

mach number, with speeds in the test section up to 400 km/h (M = 0.3).

b) High speed wind tunnel: High subsonic wind tunnels (0.4 < M < 0.75) or transonic

wind tunnels (0.75 < M < 1.2) are designed on the same principles as the subsonic

wind tunnels. Transonic wind tunnels are able to achieve speeds close to the speeds of

sound.

c) Supersonic wind tunnel: A supersonic wind tunnel is a wind tunnel that produces

supersonic speeds (1.2<M<5) .

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d) Hypersonic wind tunnel: A hypersonic wind tunnel is designed to generate a

hypersonic flow field in the working section. The speed of these tunnels varies from

Mach 5 to 15.

1.7 Analysis of High Speed Train Nose using Different Geometry

In this project we analyzed the following 4 models of the train nose to understand the

pressure acting on the face of the high speed train. The described side sectional views

are obtained from different curves. Mainly ellipse and parabola curves are taken to

develop sections. The various shapes are derived from general high speed train

geometry of different countries.

Figure 3 Model A: Section of straight edge, Model B: Section of elliptical curves, Model C: Section of

parabolic segment, Model D: Section of parabola curves – for dimensions refer appendix

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Table 2 (Input Parameters)

STAGNATION PROPERTIES OF HIGH SPEED TRAIN NOSE

INPUT PARAMETERS

Train speed (Km/h) 320

Air pressure (Pa) 101325

Temperature (K) 300

Gas const (J/kg K) 287

Cp/Cv 1.4

For generating the mesh , we used the mesh enhancement features like inflation.

Figure 4 (Mesh for Model A)

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Mesh Statistics for Model A

Total number of nodes 397885

Total number of tetrahedral 2212594

Total number of pyramids 1618

Total number of prisms 8904

Total number of elements 2223116

Figure 5 (Mesh for Model B)

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Mesh Statistics for Model B



Total number of faces 64054


Figure 6(Mesh for Model C)

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Mesh Statistics for Model C






Figure 7(Mesh for Model D)

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Mesh Statistics for Model D






1.7.1 Input Parameters

Component Feature Details

CFX-Pre User Mode General Mode

Analysis Type Steady State

Fluid Type Ideal Gas

Domain Type Single Domain

Turbulence Model Shear Stress Transport

Heat Transfer Isothermal

Boundary Conditions Inlet (Subsonic)

Outlet (Subsonic)

Side Wall: Free-Slip

Body: No-Slip

Timestep Physical Time Scale

CFX-Solver Manager Parallel processing

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1.8 Results

1.8.1 Top view configurations

The design for top sections is made on basis of smoother flow around the nose body,

less pressure gradient and relatively low stagnation area. The main criterion to adopt

for optimum design is drag and minimum static pressure.

When considering the top view (Fig 8.), we can see that the peak pressure is achieved

in the Model D with the maximum value of 4995 Pa. At the same time Model B has

the least pressure of 4851 Pa. The rectangular portion of the Model D is the reason for

having the maximum drag stagnation area. Model B appears to be the optimum shape

to have minimum value of the pressure.

Figure 8 (Figure showing the pressure distribution for the four geometries - Top view)

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Smoother streamlines on side wall plays a vital role to keep train system with track.

This face can be seen in the Model B which have smooth transition without any

stagnation area being created on the sidewalls.

1.8.2 Side View Configuration

In this view as shown in fig 9 we can see that the Model C offers a large resistance to

speed with quite large stagnation area.

Figure 9 (Figure showing the pressure distribution for the four geometries - side view)

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The main reason to analyze the side section is to observe the negative pressure,

control vortex generation and minimizing the coefficient of moment. Because the

coefficient of moment must be less for the stability of the train on the track and this is

done by keeping the coefficient of lift to be minimum. The coefficient of drag is

calculated later in the project.

Figure 10 (Velocity Streamlines)

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Velocity Streamlines :

In Fig. 11 we can see that velocity streamlines travel smoothly over the streamline

bodies. We can observe in the plot, the red regions in the velocity field , where the

velocity is maximum. Pressure reduces in those regions since velocity in high. If such

regions are more at the top, it can lead to lift. We can see in the vortex formation on

the backside of the body. The motion of the fluid swirls rapidly around a center. The

speed and rate of rotation of the fluid are greatest at the center and progressively

decrease with distance from the center. Generally in High speed trains the back end is

made similar in geometry like the front. Hence these wakes are minimized.

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Figure 11 (Pressure Contour)

In the figure 12, we can see the pressure contour. Here the highest pressure is

same in all the models but the area of the contour of not same. The smaller the

area of the contour, smaller is the force. We can see in the figure that the area for

the top two figure has relatively large area for the highest pressure. These area are

relatively small in the lower ones. Also we can observe the negative pressure

regions on the surface. For configuration Model A and Model C the stagnation

pressure as well as drag co-efficient is greater because for both configurations

portion on tip of nose may be affected due to larger surface area. The main

drawbacks for such type of shape are no smoother streamlines exists due to

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straight edge rather than curved one. So the next target is to gain some side wall

of nose inclined to get smooth streamline and reduced drag as well as pressure.

1. DRAG

The force that oppose the relative motion of an object through a fluid. Also it is

called an air resistance which acts in a direction opposite to the oncoming flow

velocity. In an open air condition, the aerodynamic drag of the train is sum of the

normal force (pressure drag) and tangential force (skin friction drag). The

reference area A is defined as the area of the orthographic projection of the object

on a plane perpendicular to the direction of motion.

The drag force due to wind (air) acting on an object can be found by:

AVCF DD

2

2

1 (1)

where: FD = drag force (N)

CD = drag coefficient (no units)

V = velocity of object (m/s)

A = projected area (m2)

ρ = density of air (kg/m3) {1.2 kg/m

3}

Here we will calculate the CD which is a number that is used to model all of the

complex dependencies of shape and flow conditions and this factor decides the

geometrical changes required to generate a better aero-dynamical shape.

http://microgravity.grc.nasa.gov/education/rocket/shaped.html

http://microgravity.grc.nasa.gov/education/rocket/airsim.html

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With the help of CFX solver, we are able to calculate the force Fd in the direction

opposite to the velocity of the train.

Using the relation mentioned above we generated the following table to compare

the drag coefficient for the different geometries.

S. No. Force FD Area A CD

Model A 14128.5 [N] 8.55 0.34

Model B 17058.8 [N] 11.822 0.30

Model C 14748.3 [N] 8.87 0.35

Model D 11895.9 [N] 8.55 0.29

From the results we can see that the value of CD for the Model B and Model D are

almost similar with the least value of the coefficient of Drag. These two profiles

had the elliptical and the parabolic curve which provides a better aerodynamic

shape to the train nose.

2. LIFT

A fluid flowing past the surface of a body exerts force on it. The component of

this force that is perpendicular to the oncoming flow direction.

AVCF LL

2

2

1 (2)

where: FL = drag force (N)

CL = drag coefficient (no units)

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V = velocity of object (m/s)

A = projected area (m2)

ρ = density of air (kg/m3) {1.2 kg/m

3}

S. No. Force FD Area A CD

Model A 2355.09 31.01 0.016

Model B 3960.55 25.09 0.033

Model C 3177.34 10.3 0.065

Model D 5235.74 18 0.061

4.8 Closure

The guidelines set up for shape optimization of high speed train nose is very good

approach to have the best geometrical shape. The commercial CFX package for

flow simulation is one of the best tools to investigate the flow without having the

real wind tunnel. The study has been done in direction of shape optimization is

not limited to geometry but can also be extended to analyze the behavior of front

cab in storm and cross wind.

I would like to thanks Prof. Vanslooten, for the guidance and his presence during

executing the project.I would also like to thank him for giving a good

understanding of the mesh element in this classes.

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1.9 Appendix

1.9.1 CCL for Case A

+---------------------------------------------+ | | | CFX Command Language for Run | | | +------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value

END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0

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Domain Type = Fluid Location = B110 BOUNDARY: body Boundary Type = WALL Location = Default 2D Region BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END

END END BOUNDARY: wall Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END

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TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 100 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END

END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/final_002.res.def END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END

1.9.2 CCL for Case B

+---------------------------------------------------------+ | | | CFX Command Language for Run | | | +---------------------------------------------------------+ LIBRARY: MATERIAL: Air at 25 C Material Description = Air at 25 C and 1 atm (dry) Material Group = Air Data, Constant Property Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Density = 1.185 [kg m^-3] Molar Mass = 28.96 [kg kmol^-1] Option = Value END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END

DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-02 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END THERMAL EXPANSIVITY: Option = Value Thermal Expansivity = 0.003356 [K^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K]

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Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0 Domain Type = Fluid Location = B39 BOUNDARY: Default Domain Modified Default Boundary Type = WALL Location = \ F47.39,F48.39,F49.39,F50.39,F51.39,F52.39,F53.39,F54.39,F55.39,F56.39\ ,F57.39 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM:

Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air at 25 C Option = Material Library MORPHOLOGY: Option = Continuous Fluid END

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END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 300 [K] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END

END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model2.def INITIAL VALUES SPECIFICATION:

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INITIAL VALUES CONTROL: Continue History From = Initial Values 1 Use Mesh From = Solver Input File END INITIAL VALUES: Initial Values 1 File Name = /ifs/user/mandeeps/model2_012.res Option = Results File END END END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END

1.9.3 CCL for Case C

+--------------------------------------------------------+ | | | CFX Command Language for Run | | | +--------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance

Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm]

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Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0

Domain Type = Fluid Location = B73 BOUNDARY: Default Domain Modified Default Boundary Type = WALL Location = \ F100.73,F101.73,F102.73,F103.73,F80.73,F81.73,F82.73,F83.73,F84.73,F8\ 5.73,F86.73,F87.73,F88.73,F89.73,F90.73,F91.73,F92.73,F93.73,F94.73,F\ 95.73,F96.73,F97.73,F98.73,F99.73 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END

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END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C]

Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL:

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EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.12500, 0.12500, 0.12500, 0.12500, \ 0.12500, 0.12500, 0.12500, 0.12500 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model3revised.def INITIAL VALUES SPECIFICATION: INITIAL VALUES CONTROL: Continue History From = Initial Values 1 Use Mesh From = Solver Input File END INITIAL VALUES: Initial Values 1 File Name =

/ifs/user/mandeeps/model3revised_006.res Option = Results File END END END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 8 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*8 END END END END

1.9.4 CCL for Case D

+--------------------------------------------------------+ | | | CFX Command Language for Run | | | +--------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END

THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0 Domain Type = Fluid Location = B153 BOUNDARY: Default Domain Modified

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Default Boundary Type = WALL Location = \ F160.153,F161.153,F162.153,F163.153,F164.153,F165.153,F166.153,F167.1\ 53,F168.153,F169.153,F170.153,F171.153,F172.153,F173.153,F174.153,F17\ 5.153,F176.153,F177.153,F178.153,F179.153,F180.153,F181.153,F182.153,\ F183.153,F184.153,F185.153,F186.153,F187.153,F188.153,F189.153,F190.1\ 53,F191.153,F192.153,F193.153,F194.153,F195.153,F196.153,F197.153,F19\ 8.153,F199.153,F200.153,F201.153,F202.153,F203.153,F204.153,F205.153,\ F206.153,F207.153,F208.153,F209.153,F210.153,F211.153,F212.153,F213.1\ 53,F214.153,F215.153,F216.153,F217.153 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET

Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Eddy Length Scale = 1 [m] Fractional Intensity = 0.05 Option = Intensity and Length Scale END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END

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END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA:

Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000

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END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model4.def END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END

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1.9.5 Convergence Residual Plots

Figure 12(Model A)

Figure 13(Model B)

Figure 14(Model C)

Figure 15(Model D)

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1.9.6 Dimensions for the Model

MODEL A

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MODEL B

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MODEL C

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MODEL D

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1.9.7 References :

1. TIAN HONG-qi “Formation mechanisms of aerodynamic drag of high-speed train

and some reduction measures” J.Cent. South Univ. Technol. (2009) 16:0166- 0171.

2. E. Lorriaux, N. Bourabaa and F. Monnoyer “Aerodynamic optimization of railway

motor coaches” University of Valenciennes, France.

3. Samuel Holmes, Martin Schroder, Elton Toma “High Speed passanger and intercity

train aerodynamic computer modeling”, The 2000 International Mechanical

Engineering Congress & Exposition November 5-10, 2000, Florida.

4. Milan Schuster “CFD Methods in industrial applications – Vehicle external

aerodynamics and aerodynamic interaction of moving vehicles” XXI ICTAM, 15-21

August 2004, Poland.

5. Jongsoo Lee and Junghui Kim “Approximate optimization of high-speed train nose

shape for reducing micropressure wave”, Struct Multidisc Optim (2008).

6. Charles-Andre LEMARIE, Nachida BOURABAA and Francois MONNOYER

“Aerodynamic optimization in railway transportation:numerical and experimental

approach”

7. CFX Tutorials - Bluntbody

8. Wikipedia.com

cfx project

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