I've altered a design that was made by my previous co-workers, but it looks like there are strange things happening with the air flow simulation. I've added a rear wing to a car design, but it looks like the airflow just passes through my wing. When I simulate an airflow on the wing itself (not in an assembly), the airflow is displayed correctly (with vortices on the wing tips etc.). The wing is a lofted part part which is knitted to a solid, so I don't think it's a surface problem (I've encountered the same problem caused by the car being partly designed as a surface. This is fixed with the 'knit surface' tool). What is causing this problem and how can I solve it? Btw, I'm new to Solidworks.
I already reviewed your model and the problem is that the flap has some solids that are intertwined, that prevents the simulator to consider a coherent solid grid.
The solution is to model the flap as a one and only solid, which must not cross with the vehicle.