# Lift Coefficient for Vehicle Simulation

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 March 3, 2016, 14:33 Lift Coefficient for Vehicle Simulation #1 New Member   Steve Join Date: Dec 2015 Posts: 3 Rep Power: 6 Hey everyone, I've set up a simulation for a VW Beetle and am currently only getting Cl and Cd values for the vehicle as a whole. I'd like to get Cl for the front and rear separately as well, but can't see how to do this in Star CCM+. I've currently got it set up so that reports have the car body as their input parts, I can't see how I could set it up to get two separate lift coefficients acting on that body. Any help would be greatly appreciated. Steve

 April 6, 2016, 10:09 #2 New Member   Magnus Join Date: Feb 2015 Posts: 7 Rep Power: 6 Hi Steve, This is a bit late but if you haven't solved it yet... You can make a field function in order to get how much each cell on the surface of your vehicle is contributing to the Cl or Cd. Something similar to this: Code: `(\${Fx_cell}/\$\$Area.mag())/(0.5*\${rho}*pow(\${vcar},2))` Where Fx_cell is another field function for the force in x-direction of the cell. Something like this: Code: `Fx_cell = ((\$\${Area}[0]*\${MeanCPMonitor}*0.5*\${rho}*pow(\${vcar},2))+(\${MeanWallShearXMonitor}*\$\$Area.mag()))` After that you make two thresholds under derived parts. Set the scalar field to Centroid to cover half the car for each threshold. As parts you choose the surfaces of the car. To get the values make two sum reports (one for each half), as Scalar field you choose the one previously defined (Cl/Cd for each cell) and as parts you choose the threshold you've created. Cheers, Magnus

 Tags lift coefficent, star ccm+, vehicle aerodynamics, vehicles