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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