Strange problem

Steven

Hi

Thanks to all response so far on this forum, especially the few regualr posters..

I have two idential simulations, both of an airfoil, both have exactly the same setup (mesh spacing etc)

There is one difference, in one simuaiton the airfoil it self is inclined to simulate AOA and on the other the incline is simlated by cartesian velocity components. In both cases the inlet is a half cylinder on the front of a rectangualr tube (aka windtunnel).

The inclined airfoil shows seperation (does not totally converge due to transient effects) and resonable lift and drag quantites. The cartesian simulation does not show seperation and also the drag value is negative ie the wing produces thrust?! The wind tunnel is much bigger than the model so wall effects should noot be an issue.

Ive been told the method of using cartesian velociies is fine but why is there this massive difference??

Thanks in advance (again!)

Steven