Wind Tunnel Simulation

Engineer name: rahulp

Wed May 24 10:22:14 2017 India Daylight Time

Product of Altair Engineering Inc.

http://www.altair.com

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Contents

1 Summary 3

2 Dimensions 3

3 Mesh 4

4 Boundary Conditions and Solution Strategy 6

5 Results 6

6 References 12

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1 Summary

This report summarizes the results of an externalaerodynamic CFD analysis performed by Altair’s VirtualWind Tunnel, leveraging AcuSolve’s CFD technology.

The first section provides a brief overview of the run and its results.

AcuSolve version 2017Simulation type steadyElement count 85563266Run time ( Elapse time ) 16.010 hWind Tunnel Inlet 25.00 0.00 0.00 m/sDrag coefficient, Cd 0.334Lift coefficient, Cl 0.037

Table 1: Problem Information

2 Dimensions

This sections contains geometric dimensionsrelated to the wind tunnel and the body.

Wind tunnel, bounding box [ 0.105, 3.785], [-0.515, 0.537], [ 0.000, 1.160]Body, bounding box [ 1.234, 1.464], [-0.037, 0.059], [-0.001, 0.115]Wind tunnel dimension 3.680 m x 1.052 m x 1.160 m.Body dimension 0.230 m x 0.096 m x 0.116 m.Frontal ref. area, Aref 0.008483 m2

Blockage ratio % 0.695145535597Distance inflow - body 1.129 m

Table 2: Geometric Dimensions

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Figure 1: Virtual Wind Tunnel

3 Mesh

This section contains mesh statistics and screenshots of several cutting planes through the mesh.

Numb. of nodes 16596571Numb. of elements 85563266Numb. of refinement zones 3

Table 3: Mesh statistics

Figure 2 Symmetry planeFigure 3 Cross section

Table 4: Cutting planes through mesh

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Figure 2: Mesh in Flow Direction

Figure 3: Mesh in Cross Direction

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4 Boundary Conditions and Solution Strategy

In this section the boundary conditions and the setup for the CFD run are listed.

Wind Tunnel Inlet 25.00 0.00 0.00 m/sWind Tunnel Outlet Pressure outletSlip Walls Top, right, left faces of wind tunnelNo-slip Walls wind tunnel ground, body, wheels, heat-exchange

Table 5: Boundary conditions

Simulation type steadyNumber of time steps 25Turbulence model Spalart-AllmarasMoving ground FalseRotating wheels False

Table 6: Solution Strategy

Density 1.225 kg/m3Dynamic Viscosity 1.8e-005 kg/m-sec

Table 7: Material Model

5 Results

In this section the results of the CFD run are reported. Table 8 gives an overview of the different result types.

Table 9 Drag, lift and cross coefficient of individual parts and their totalsTable 10 Drag area of individual parts and their totalsFigure 4 Drag, lift and cross coefficient historyFigure 11 Pressure contours on bodyFigure 12 Pressure coefficient on body surfaceFigure 13, 14, 15 Body Surface y+ contoursFigure 16, 17 Streamlines around body

Table 8: Results

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Surface Drag Coefficient Lift Coefficient Cross CoefficientBike-1 0.33427 0.03697 0.00062Total 0.33427180329 0.0369663290909 0.000616990991554

Table 9: Coefficients

Surface Drag AreaBike-1 0.00284Total 0.00283562770731

Table 10: Drag Areas

To compute the above aerodynamic coefficients, the following equations are used

• Drag coefficient, Cd = 2×Fx

rho×v2×Aref

• Lift coefficient, Cl = 2×Fz

rho×v2×Aref

• Cross coefficient, Cc = 2×Fy

rho×v2×Arefwith

• Fx, Fy, andFz, forces are acting on the body in x, y and z directions, respectively

• rho is density of fluid (1.225 kg/m3)

• v is free stream velocity

• Aref is frontal projected area of the object

• Drag area, Cd × Aref = 2×Fx

rho×v2

• Pressure coefficient, Cp =p−pinfinity

0.5×rho×v2

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Figure 4: Coefficients

Figure 5: pressure on Section Cut 1

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Figure 6: velocity magnitude on Section Cut 1

Figure 7: x-velocity on Section Cut 1

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Figure 8: y-velocity on Section Cut 1

Figure 9: z-velocity on Section Cut 1

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Figure 10: eddy viscosity on Section Cut 1

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Figure 11: Body Surface Pressure Contours

Figure 12: Body Surface Pressure Coefficient

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Figure 13: Body Surface y+ Front View

Figure 14: Body Surface y+ Rear View

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Figure 15: Body Surface y+ Bottom View

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Figure 16: Stream lines

Figure 17: Stream lines Side View

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6 References

• Altair Engineering Inc, 2015, Virtual Wind Tunnel, Online Documentation

• Altair Engineering Inc, 2015, AcuSolve Command Reference Manual.

• Hucho, W.-H., 1997, Aerodynamics of Road Vehicles, SAE, ISBN 0-7680-0029-7.

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