A Technical Note on the appropriate CFD boundary conditions for the prediction of ground effect aerodynamics

The accurate prediction of ground effect aerodynamics is an important aspect of wing-in-ground effect vehicle (WIG) design. Computational fluid dynamics (CFD) solutions are useful alternatives to expensive (especially in the case of ground effect) wind-tunnel testing. However, the incorporation of the rigid surface effects often leads to confusion due to such a model being in a vehicle fixed reference frame (air moving, vehicle fixed) rather than the real-life situation of a ground fixed reference frame (air fixed, vehicle moving).