Ahmed body flow computation using Computational Fluid Dynamics

8/10/2019 Ahmed body flow computation using Computational Fluid Dynamics

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Solved with COMSOL Multiphysics 4.3b

2 | A I R F L O W O V E R A N A H M E D B O D Y 2 0 1 3 C O M S O L

slant angle of 25 degrees, which is the same slant angle used in Ref. 3.

Figure 1: Ahmed body with 25 degree slant of the rear face.

The body is placed in a flow domain that is 8L-by-2L-by-2L

(length-by-width-by-height), with its front positioned 2Lfrom the flow inlet face.

Mirror symmetry reduces the computational domain by half, as shown in Figure 2.

Figure 2: The size of the computational domain is reduced by mirror symmetry.

Length

Width

Height

8L

2L

L

2L

Inlet

Outlet

Wall function

Slip

Symmetry


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2 0 1 3 C O M S O L 3 | A I R F L O W O V E R A N A H M E D B O D Y

T U R B U L E N C E M O D E L

The Reynolds number base on the length of the body, L, and the inlet velocity is

2.77106which means that the flow is turbulent. The k-turbulence model will beapplied to account for the turbulence. The k-turbulence model is described in

Theory for the Turbulent Flow User Interfacesin the CFD Module Users Guide.

B O U N D A R Y C O N D I T I O N S

Air enters the computational domain at a freestream velocityu=40 m/s normal to the

inlet surface. Experimental inlet conditions from Ref. 3are used.

At the outlet, a Pressure condition is applied.

The floor of the flow domain and surface of the Ahmed body are described by wall

functions. Wall functions could also be applied to the outer wall and the ceiling of the

wind tunnel. Their main effect on the flow around the body is however to keep the

flow contained, and it will therefore suffice to model them as slip walls.

The temperature is assumed to be 293 K and the reference pressure is 1 atm.

M E S H I N G

A common mesh size in Ref. 3is half a million cells for simulations with wall functions.

However, those simulations do not include the stilts (the legs that support the body),

and the computational domains are smaller. Hence, you can expect to need an even

larger mesh in this simulation to resolve the flow. How large is however difficult to

know in advance.

There are two important aspects of the meshing. The first is to resolve the flow in thewake. To achieve this, additional mesh control entities are introduced in the geometry.

These entities are advantageous to normal geometrical entities since they are removed

whence they are completely meshed. A smoothing algorithm will then smooth the

mesh locally in order to minimize gradients in the mesh size. Also, it is easier to

introduce boundary layer mesh when the control entities are removed.

Results and DiscussionA key figure for the Ahmed body is the total drag coefficient, CD, which is defined as

(1)F

Ap------- CD

u2

2-----------=
http://../cfd/cfd_ug_fluidflow_single.pdfhttp://../cfd/cfd_ug_fluidflow_single.pdf


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whereFis the total drag force on the body, Apis area of the body projected on a plane

perpendicular to the flow direction (that is, the xz-plane), is the density

(approximately equal to 1.2 kg/m3), and uis the freestream velocity (equal to 40 m/s). Apcan be calculated from geometrical data and is equal to 0.115m

2including the

stilts. The contributions to CDare commonly reported as the pressure coefficients on

front, slant, and base and the skin friction drag coefficient. These numbers are given in

Table 1. Note that the numbers given by the postprocessing tools correspond to half

the body, and hence, Apmust be replaced by Ap/2when calculating the entries of

Table 1.

As can be seen, most contributions are in reasonable agreements with experiments.

The total drag is very well predicted, but the individual contributions deviate from

experimental values.The pressure coefficient on the front is too high and the skin friction too low. Ref. 4

uses two different versions of the k-model and two different wall function

formulations and all combinations show this behavior. It can probably be tributed to

the fact that wall functions are not very good at predicting the transition observed in

the experiments to take place on the front and roof of the body.

The low value of the slant pressure drag coefficient can be understood by looking at

Figure 3, which shows streamlines in the symmetry plane. Experimental results

indicate that the flow along the slant is attached almost everywhere and that there are

two small recirculation regions behind the base. The computational results capture this

behavior, but the recirculation zones are a little bit too large. The pressure drag

coefficient, especially for the slant, is very sensitive to the exact shape and location of

the recirculation regions.

TABLE 1: DRAG COEFFICIENTS

CP FRONT CP SLANT CP BASE SKIN FRICTION TOTAL DRAG

Measurements 0.020 0.140 0.070 0.055 0.285

k- 0.039 0.109 0.073 0.038 0.283


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Figure 3: Streamlines in the symmetry plane.

Figure 4shows a 3D plot of the streamlines behind the Ahmed body. The thickness of

the lines is given by the turbulent kinetic energy. The most notable feature of the flow

field is an empty region behind the body. The streamlines on the edge of the region

are thick but with low velocity magnitude. This region is constituted of therecirculation vortices visible in Figure 3. The region ends when vortices from the


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trailing edges of the body merge into two counter rotating vortices (only one vortex

is visible because the other vortex is on the other side of the symmetry plane).

Figure 4: Streamlines behind the Ahmed body. The streamlines are colored by the velocitymagnitude and their thickness is proportional to the turbulent kinetic energy.


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More details are visible in Figure 5and Figure 6, which show arrow plots of the

velocity in thexz-plane 80 mm and 200 mm downstream of the body, respectively.

Figure 5: Velocity in the xz-plane at y= L+ 0.08m.

The flow pattern 80mm downstream of the body shows two major vortices, one

emanating from the outer edge of the slant and one emanating from the interaction

between the floor and the stilts. The flow is qualitatively equal to the experimental

results (Ref. 2). There are however quantitative differences. The upper vortex is smaller


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compared to experiments while the lower vortex is more pronounced than in the

experiments.

Figure 6: Velocity in the xz-plane at y= L+ 0.20 m.

The flow pattern 200mm downstream of the body shows that one major vortex is

beginning to form but remains of the separate vortices can still be detected. The

formation is, however, not proceeded as far as in the experiments.

In conclusion, the major features of the flow are well captured by the k-model, but

there are details that deviate from experimental data. This finding is in agreement with

other RANS simulations of the Ahmed body (Ref. 3).

References

1. S.R. Ahmed and G. Ramm, Some Salient Features of the Time-Averaged Ground

Vehicle Wake, SAE-Paper 840300, 1984.

2. H. Lienhart and S. Becker, Flow and Turbulence Structure in the Wake of a

Simplified Car Model, SAE 2003 World Congress, SAE Paper 2003-01-0656,

Detroit, Michigan, USA, 2003.


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G L O B A L D E F I N I T I O N S

Interpolation 1

1 Right-click Global Definitionsand choose Functions>Interpolation.

2 In the Interpolationsettings window, locate the Definitionsection.

3 From the Data sourcelist, choose File.

4 Click the Browsebutton.

5 Browse to the models Model Library folder and double-click the file

ahmed_body_Uin.txt.

6 Find the Functionssubsection. In the table, enter the following settings:

7 Locate the Interpolation and Extrapolationsection. From the Extrapolationlist,

choose Specific value.

8 Locate the Unitssection. In the Argumentsedit field, type m.

9 In the Functionedit field, type m/s.

10 Locate the Definitionsection. Click the Importbutton.

Interpolation 2





5 Browse to the models Model Library folder and double-click the fileahmed_body_Vin.txt.



Sb H_body+Cl-Sl*sin(25

[deg])

Slant base

Rl L-Sl*cos(25[deg]) Roof length

Function name Position in fileUin 3

Function name Position in file

Vin 3

Name Expression Description


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Interpolation 3






ahmed_body_Win.txt.


7 Locate the Interpolation and Extrapolationsection. From the Extrapolationlist,

chooseSpecific value

.8 Locate the Unitssection. In the Argumentsedit field, type m.



Interpolation 4


2 In the Interpolationsettings window, locate the Definitionsection.3 From the Data sourcelist, choose File.



ahmed_body_kin.txt.



8 In the Functionedit field, type m^2/s^2.



Win 3


kin 3


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G E O M E T R Y 1

Import 1

1 In the Model Builderwindow, under Model 1right-click Geometry 1and choose

Import.

2 In the Importsettings window, locate the Importsection.



ahmed_body.mphbin.

5 Click the Importbutton.

Block 1

1 In the Model Builderwindow, right-click Geometry 1and choose Block.

2 In the Blocksettings window, locate the Size and Shapesection.

3 In the Widthedit field, type 2*L.

4 In the Depthedit field, type 8*L.

5 In the Heightedit field, type 2*L.

6 Locate the Positionsection. In the xedit field, type -L.

7 In the yedit field, type -2*L.

8 Click the Build Selectedbutton.

9 Click the Go to Default 3D Viewbutton on the Graphics toolbar.

Block 2

1 Right-click Geometry 1and choose Block.

2 In the Blocksettings window, locate the Size and Shapesection.

3 In the Widthedit field, type L.

4 In the Depthedit field, type 8*L.

5 In the Heightedit field, type 2*L.

6 Locate the Positionsection. In the xedit field, type -L.

7 In the yedit field, type -2*L.


Difference 1

1 Right-click Geometry 1and choose Boolean Operations>Difference.

2 Select the object blk1only.


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3 In the Differencesettings window, locate the Differencesection.

4 Under Objects to subtract, click Activate Selection.

5 Select the objects imp1and blk2only.


Cylinder 1

1 Right-click Geometry 1and choose Cylinder.

2 In the Cylindersettings window, locate the Size and Shapesection.

3 In the Radiusedit field, type 2.2*L.

4 In the Heightedit field, type L.

5 Locate the Positionsection. In the yedit field, type 0.2*L.

6 In the zedit field, type -0.1*L.

7 Locate the Axissection. From the Axis typelist, choose x-axis.

Convert to Surface 1

1 Right-click Geometry 1and choose Conversions>Convert to Surface.

2 Select the object cyl1only.

Delete Entities 1

1 Right-click Geometry 1and choose Delete Entities.

2 On the object csur1, select Boundaries 1 and 36 only. These are all surfaces of the

cylinder, except the curved surface behind the body.


Union 1

1 Right-click Geometry 1and choose Boolean Operations>Union.

2 Select the objects del1and dif1only.


Delete Entities 2

1Right-click

Geometry 1and choose

Delete Entities.

2 On the object uni1, select Boundaries 10 and 16 only. These are the boundaries that

protrude above and beneath the channel.


Hexahedron 1

1 Right-click Geometry 1and choose More Primitives>Hexahedron.


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2 In the Hexahedronsettings window, locate the Verticessection.

3 In row 1, set yto Land set zto Cl.

4 In row 2, set yto 2*Land set zto Cl.

5 In row 3, set xto D/2, set yto 2*Land set zto Cl.

6 In row 4, set xto D/2, set yto L, and set zto Cl.

7 In row 5, set yto Land set zto Sb.

8 In row 6, set yto 2*Land set zto Sb.

9 In row 7, set xto D/2, set yto 2*Land set zto Sb.

10 In row 8, set xto D/2, set yto L, and set zto Sb.

Hexahedron 2




4 In row 2, set yto 2*Land set zto Sb.

5 In row 3, set xto D/2, set yto 2*Land set zto Sb.

6 In row 4, set xto D/2, set yto Land set zto Sb.

7 In row 5, set yto Land set zto H_body+Cl+0.01[m].

8 In row 6, set yto 2*Land set zto H_body+Cl+0.01[m].

9 In row 7, set xto D/2, set yto 2*Land set zto H_body+Cl+0.01[m].

10 In row 8, set xto D/2, set yto Land set zto H_body+Cl+0.01[m].

Hexahedron 3




4 In row 2, set yto Land set zto H_body+Cl+0.01[m].

5 In row 3, set xto D/2, set yto Land set zto H_body+Cl+0.01[m].

6 In row 4, set xto D/2, set yto Land set zto Sb.

7 In row 5, set yto Rland set zto H_body+Cl.

8 In row 6, set yto Rland set zto H_body+Cl+0.01[m].

9 In row 7, set xto D/2, set yto Rl and set zto H_body+Cl+0.01[m].

10 In row 8, set xto D/2, set yto Rland set zto H_body+Cl.


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The model geometry is now complete.

The completed Ahmed Body geometry.

Create an explicit selection of the boundaries of the body.

D E F I N I T I O N S

Explicit 1

1 In the Model Builderwindow, under Model 1right-click Definitionsand choose

Selections>Explicit.

2 In the Explicitsettings window, locate the Input Entitiessection.

3 From the Geometric entity levellist, choose Boundary.

4 Click the Select Boxbutton on the Graphics toolbar.

5 Select Boundaries 511 and 1316 only.

6 Right-click Model 1>Definitions>Explicit 1and choose Rename.

7 Go to the Rename Explicitdialog box and type Bodyin the New nameedit field.

8 Click OK.

9 Click the Transparencybutton on the Graphics toolbar.


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M A T E R I A L S

Mater ial Browser

1 In the Model Builderwindow, under Model 1right-click Materialsand choose Open

Material Browser.

2 In the Material Browsersettings window, In the tree, select Built-In>Air.

3 Click Add Material to Model.

Turbulent Flow, k-

Wall 21 In the Model Builderwindow, under Model 1right-click Turbulent Flow, k-and

choose Wall.

2 In the Wallsettings window, locate the Boundary Conditionsection.

3 From the Boundary conditionlist, choose Slip.


Symmetry 11 In the Model Builderwindow, right-click Turbulent Flow, k-and choose Symmetry.

2 Select Boundary 1 only.

Inlet 1

1 Right-click Turbulent Flow, k-and choose Inlet.


3 In the Model Builderwindow, click Inlet 1.4 In the Inletsettings window, locate the Boundary Conditionsection.

5 Click the Specify turbulence variablesbutton.

6 In the k0edit field, type kin(x,z).

7 In the 0edit field, type spf.C_mu*kin(x,z)^2*spf.rho/

(10*1.814e-5[Pa*s]).

8 Locate the Velocitysection. Click the Velocity fieldbutton.9 In the u0table, enter the following settings:

Uin(x,z) x

Vin(x,z) y

Win(x,z) z


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Change to unidirectional constraints to avoid reaction forces in the pressure from the

constraint for .

10 In the Model Builderwindows toolbar, click the Showbutton and select Advanced

Physics Optionsin the menu.

11 Click to expand the Constraint Settingssection. From the Apply reaction terms onlist,

choose Individual dependent variables.

Outlet 1

1 In the Model Builderwindow, right-click Turbulent Flow, k-and choose Outlet.


3 In the Outletsettings window, locate the Boundary Conditionsection.

4 From the Boundary conditionlist, choose Pressure.

M E S H 1

Size

1 In the Model Builderwindow, under Model 1right-click Mesh 1and choose Edit

Physics-Induced Sequence.

2 In the Model Builderwindow, under Model 1>Mesh 1click Size.

3 In the Sizesettings window, locate the Element Sizesection.

4 Click the Custombutton.

5 Locate the Element Size Parameterssection. In the Maximum element sizeedit field,

type 0.1.

6 In the Minimum element sizeedit field, type 0.0025.

7 In the Resolution of curvatureedit field, type 0.4.

8 In the Resolution of narrow regionsedit field, type 0.5.

Size 1

1 In the Model Builderwindow, under Model 1>Mesh 1click Size 1.

2 In the Sizesettings window, locate the Geometric Entity Selectionsection.

3 Click Clear Selection.

4 Select Boundaries 23, 25, and 27 only.




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7 Locate the Element Size Parameterssection. Select the Maximum element sizecheck

box.

8 In the associated edit field, type 0.05.


Size 2

1 In the Model Builderwindow, right-click Mesh 1and choose Size.







box.


Size 3

1 Right-click Mesh 1and choose Size.







box.


Size 4








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box.


Size 5



3 From the Geometric entity levellist, choose Edge.

4 Select Edges 35 and 36 only.

5 Locate the Element Sizesection. Click the Custombutton.


box.


Free Tetrahedral 1

1 In the Model Builderwindow, under Model 1>Mesh 1right-click Corner Refinement 1

and choose Disable.2 In the Model Builderwindow, under Model 1>Mesh 1click Free Tetrahedral 1.

3 In the Free Tetrahedralsettings window, locate the Domain Selectionsection.


5 Select Domain 3 only.

Size 1

1 Right-click Model 1>Mesh 1>Free Tetrahedral 1and choose Size.



4 Locate the Element Size Parameterssection. Select the Maximum element growth rate

check box.


Free Tetrahedral 1

Right-click Free Tetrahedral 1and choose Build Selected.

Free Tetrahedral 3

1 Right-click Mesh 1and choose Free Tetrahedral.

2 In the Free Tetrahedralsettings window, locate the Domain Selectionsection.

3 From the Geometric entity levellist, choose Domain.


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Boundary Layers 1

1 In the Model Builderwindow, under Model 1>Mesh 1click Boundary Layers 1.

2 In the Boundary Layerssettings window, locate the Domain Selectionsection.



Boundary Layer Properties 1

1 In the Model Builderwindow, expand the Boundary Layers 1node, then click

Boundary Layer Properties 1.

2 In the Boundary Layer Propertiessettings window, locate the Boundary Layer

Propertiessection.

3 In the Number of boundary layersedit field, type 6.

4 In the Thickness adjustment factoredit field, type 1.5.

Boundary Layers 1

In the Model Builderwindow, under Model 1>Mesh 1right-click Boundary Layers 1and

choose Build Selected.

Swept 1

1 Right-click Mesh 1and choose Swept.

2 In the Sweptsettings window, locate the Domain Selectionsection.

3 From the Geometric entity levellist, choose Domain.


Distribution 1

1 Right-click Model 1>Mesh 1>Swept 1and choose Distribution.

2 In the Distributionsettings window, locate the Distributionsection.

3 From the Distribution propertieslist, choose Predefined distribution type.

4 In the Number of elementsedit field, type 28.

5 In the Element ratioedit field, type 6.

6 In the Model Builderwindow, right-click Mesh 1and choose Build All.

7 In the Model Builderwindow, collapse the Mesh 1node.


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M O D E L 1

In the Model Builderwindow, right-click Model 1and choose Mesh.

M E S H 2

Reference 1

1 In the Model Builderwindow, under Model 1>Meshesright-click Mesh 2and choose

More Operations>Reference.

2 In the Referencesettings window, locate the Referencesection.

3 From the Meshlist, choose Mesh 1.

Scale 1

1 Right-click Model 1>Meshes>Mesh 2>Reference 1and choose Scale.

2 In the Scalesettings window, locate the Scalesection.

3 In the Element size scaleedit field, type 2.



M O D E L 1

In the Model Builderwindow, under Model 1right-click Meshesand choose Mesh.

M E S H 3

Reference 1

1 In the Model Builderwindow, under Model 1>Meshesright-click Mesh 3and choose

More Operations>Reference.

2 In the Referencesettings window, locate the Referencesection.

3 From the Meshlist, choose Mesh 2.

Scale 1

1 Right-click Model 1>Meshes>Mesh 3>Reference 1and choose Scale.

2 In the Scalesettings window, locate the Scalesection.

3 In the Element size scaleedit field, type 2.



M O D E L 1

1 In the Model Builderwindow, collapse the Model 1>Meshesnode.

S l d i h COMSOL M l i h i 4 3b


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Show Advanced Study Optionsto be able to apply the manual multigrid levels.

1 In the Model Builderwindows toolbar, click the Showbutton and select Advanced

Study Optionsin the menu.

S T U D Y 1

Step 1: Stationary

1 In the Model Builderwindow, expand the Study 1node.

2 Right-click Step 1: Stationaryand choose Multigrid Level.

3 In the Multigrid Levelsettings window, locate the Mesh Selectionsection.4 In the table, enter the following settings:

5 In the Model Builderwindow, right-click Step 1: Stationaryand choose Multigrid

Level.

Solver 1

1 Right-click Study 1and choose Show Default Solver.

2 In the Model Builderwindow, expand the Study 1>Solver Configurations>Solver

1>Stationary Solver 1>Iterative 1node, then click Multigrid 1.

3 In the Multigridsettings window, locate the Generalsection.

4 From the Hierarchy generation methodlist, choose Manual.

5 In the Model Builderwindow, collapse the Study 1>Solver Configurations>Solver

1>Stationary Solver 1>Iterative 1node.

6 In the Model Builderwindow, expand the Study 1>Solver Configurations>Solver

1>Stationary Solver 1>Iterative 2node, then click Multigrid 1.

7 In the Multigridsettings window, locate the Generalsection.

8 From the Hierarchy generation methodlist, choose Manual.

9 In the Model Builderwindow, collapse the Study 1>Solver Configurations>Solver1>Stationary Solver 1>Iterative 2node.

10 In the Model Builderwindow, collapse the Study 1>Solver Configurations>Solver

1>Stationary Solver 1node.

11 In the Model Builderwindow, collapse the Solver 1node.

12 In the Model Builderwindow, right-click Study 1and choose Compute.

Geometry Mesh

Geometry 1 mesh2

Solved with COMSOL Multiphysics 4 3b


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It is advisable to disable the automatic update of plots when working with large 3D

models.

R E S U L T S

1 In the Resultssettings window, locate the Result Settingssection.

2 Clear the Automatic update of plotscheck box.

Investigate the lift-off in viscous units to verify that the wall resolution is sufficient.

R E S U L T S

Wall Resolution (spf)

1 In the Model Builderwindow, under Resultsclick Wall Resolution (spf).

2 Click the Plotbutton.

The wall lift-off is larger than 11.06 on most of the floor, but it is close to 11.06 on

most of the body and can hence be considered to be acceptable.

Wall lift-off in viscous units.

Solved with COMSOL Multiphysics 4 3b


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Velocity (spf)

1 In the Model Builderwindow, expand the Results>Velocity (spf)node, then click Slice

1.2 In the Slicesettings window, locate the Plane Datasection.

3 From the Entry methodlist, choose Coordinates.

4 In the x-coordinatesedit field, type 0.15.


The slice plot of the velocity clearly shows the recirculation zone behind the body.

The result looks smooth which further supports the assumption that the resolutionis acceptable.

Slice plot at x=0.15[m] of the velocity magnitude.

To evaluate the input to calculate the entries in Table 1, perform the following steps:

R E S U L T S

Derived Values

1 In the Model Builderwindow, under Resultsright-click Derived Valuesand choose

Integration>Surface Integration.


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4 Locate the Parameterizationsection. From the x- and y-axeslist, choose yz-plane.


2D Plot Group 4

1 In the Model Builderwindow, right-click Resultsand choose 2D Plot Group.

2 In the 2D Plot Groupsettings window, locate the Datasection.

3 From the Data setlist, choose Surface 3.

4 Right-click Results>2D Plot Group 4and choose Streamline.

5 In the Streamlinesettings window, locate the Expressionsection.

6 In the x componentedit field, type v.

7 In the y componentedit field, type w.

8 Locate the Streamline Positioningsection. In the Pointsedit field, type 30.


The following steps reproduce Figure 4:

Data Sets1 In the Model Builderwindow, under Resultsright-click Data Setsand choose Solution.

2 Right-click Results>Data Sets>Solution 2and choose Add Selection.

3 In the Selectionsettings window, locate the Geometric Entity Selectionsection.


5 From the Selectionlist, choose Body.


3D Plot Group 5


2 Right-click 3D Plot Group 5and choose Surface.

3 In the Surfacesettings window, locate the Datasection.

4 From the Data setlist, choose Solution 2.

5 Locate the Expressionsection. In the Expressionedit field, type 1.6 Locate the Coloring and Stylesection. Clear the Color legendcheck box.

7 From the Coloringlist, choose Uniform.

8 From the Colorlist, choose Gray.

9 Clear the Plot data set edgescheck box.

10 Right-click Results>3D Plot Group 5and choose Streamline.



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11 In the Streamlinesettings window, locate the Streamline Positioningsection.

12 From the Positioninglist, choose Start point controlled.

13 From the Entry methodlist, choose Coordinates.

14 In the xedit field, type range(0.01,0.03,0.16) range(0.01,0.03,0.16)

range(0.01,0.03,0.16) range(0.01,0.03,0.16) range(0.01,0.03,0.16).

15 In the yedit field, type -0.5*L.

16 In the zedit field, type 0.02*1^range(1,6) 0.08*1^range(1,6)

0.14*1^range(1,6) 0.2*1^range(1,6) 0.26*1^range(1,6).

17 Locate the Coloring and Stylesection. From the Line typelist, choose Tube.18 In the Tube radius expressionedit field, type k*1[s^2/m].

19 Select the Radius scale factorcheck box.

20 In the associated edit field, type 3e-4.

21 Right-click Results>3D Plot Group 5>Streamline 1and choose Color Expression.

22 In the Settingswindow, click Plot.

The following steps will reproduce Figure 5and Figure 6:

Data Sets

1 In the Model Builderwindow, under Resultsright-click Data Setsand choose Cut

Plane.

2 In the Cut Planesettings window, locate the Plane Datasection.

3 From the Planelist, choose zx-planes.

4 In the y-coordinateedit field, type L+0.08.

5 In the Model Builderwindow, right-click Data Setsand choose Cut Plane.

6 In the Cut Planesettings window, locate the Plane Datasection.

7 From the Planelist, choose zx-planes.

8 In the y-coordinateedit field, type L+0.2.

3D Plot Group 6


2 In the 3D Plot Groupsettings window, locate the Plot Settingssection.

3 Clear the Plot data set edgescheck box.

3D Plot Group 6

1 In the Model Builderwindow, under Results>3D Plot Group 5right-click Surface 1and

choose Copy.



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2 Right-click 3D Plot Group 6and choose Paste Surface.

3 Right-click 3D Plot Group 6and choose Arrow Surface.

4 In the Arrow Surfacesettings window, locate the Datasection.

5 From the Data setlist, choose Cut Plane 1.

6 Locate the Expressionsection. In the y componentedit field, type 0.

7 Locate the Coloring and Stylesection. From the Arrow lengthlist, choose Logarithmic.

8 In the Range quotientedit field, type 500.

9 Select the Scale factorcheck box.

10 In the associated edit field, type 1.25e-3.

11 In the Number of arrowsedit field, type 2500.

12 From the Colorlist, choose Black.

13 In the Model Builderwindow, under Results>3D Plot Group 6right-click Arrow Surface

1and choose Filter.

14 In the Filtersettings window, locate the Element Selectionsection.

15 In the Logical expression for inclusionedit field, type (x


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Documents

Ahmed body flow computation using Computational Fluid Dynamics