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Modified the motorBike tutorial, getting very high drag |
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October 23, 2012, 05:37 |
Modified the motorBike tutorial, getting very high drag
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Member
Ben
Join Date: Sep 2012
Posts: 40
Rep Power: 13 |
I wanted to test the drag on a car design that I had made so from the help of the users of this forum I managed to replace the motorbike with the car in the wind tunnel.
I opened the forceCoefs.dat file to view my drag coefficients, there was a huge list of very big numbers up to about 2000 and the minimum being about 1000, this was the same for lift and down force also.I forces { type forceCoeffs; functionObjectLibs ( "libforces.so" ); outputControl timeStep; outputInterval 1; patches ( "motorBike.*" ); pName p; UName U; rhoName rhoInf; // Indicates incompressible log true; rhoInf 1; // Redundant for incompressible liftDir (0 0 1); dragDir (1 0 0); CofR (0.72 0 0); // Axle midpoint on ground pitchAxis (0 1 0); magUInf 20; lRef 1.42; // Wheelbase length Aref 0.75; // Estimated <- EDIT: changed this to 100.75 and am suddenly getting lower drag coefficients, they are still very high but getting numbers like 19.0 } Please could you tell me how to fix this problem, I know the drag coefficient should only be around 0.2 but I am getting numbers up to about 5000 now. EDIT: So after changing the area I notice I am getting better results, so I am guessing I need to find the estimated area of my car to get any good results, does anyone know how I can do this through OpenFOAM or paraView, and also when it says area does it mean frontal area? Thank you Last edited by ben1793; October 24, 2012 at 11:44. |
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