Hi, I have a C type mesh of a 2D airfoil which i used for my RANS calculations. I have now extruded this profile by a given quantity through the volume>sweep function such that a 3D wing profile now existis. The extruded section of my wing now ends at the wall. Is this sufficinet for 3D DES analysis or should there be a gap between the wall and the wing to capture the effects of downwash?

Does it match your physical geometry? If not then the answer is no, if you want realistic answers. If yes then consider what your grid spacing needs to be to capture the motion scales needed.