I'm modelling a solar car in a wind tunnel in fluent using a laminar flow solver. The drag coefficient that I'm getting is very high, a value of approx 0.2, when the expected value should be about 0.1 for the specific airfoil that I'm using, what could be the possible problem?

Turbulence model! Boundary Conditions! Turbulence Intensity! Your Mesh!

Think about it and you will get close to the actual value, by the way it is very hard to predict drag in the first place!

Alan.

Drag Coefficient is the result of dividing the drag force by the kinetic energy of the free stream. Drag calculations are performed by applying the law of the wall, Check your Y+ values

And try to put a boundary layer around your model: between 6 or 7 layers at least. Start with a 1st order discretization scheme and then switch to 2nd order upwind (or QUICK if your mesh is made from hexa's.)

Good luck!

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