I like me some race car tech
This is an entire thesis written on the pressure zones and aero of wheel-wells
http://www.tfd.chalmers.se/~sinisa/i...st_Jan2010.pdf, just in case anyone wants to read up on it (almost 50 pages)
It's based on a rectangle body with smooth surfaces, it is of course theoretical and not real world. Each vehicle would be different.
"The findings indicate that addition of wheel and wheelhouse to basic model increases the drag force by 34% and 38.9% for different cases
(the addition of them to a square body for theoretical aerodynamic study). The drag and lift forces are dependent on the wheelhouse depth. Increasing wheelhouse depth increase the total drag and the total downforce forces. The results also indicates that the wheel generates lift for both cases but the bigger wheelhouse volume generates higher lift forces. The results shows the importance of considering the effect of the rotating wheel. Reducing drag forces can be a challenging task to increase the efficiency of the vehicle."
Looking at the bountiful diagrams and graphs, it appears that the wheel well is a source of both high pressure and low pressure... Lift and downforce
And the drag comes in the form of vortices off the tire itself not the spokes because the model used a solid wheel like our pizza pan covers, as well as the escaping air on the lower 1/3 of the rear of the opening (the part that you guys want to cut or vent), and the bottom edge of the wheel well below the car.
Here are a few of the diagrams I found of the most interest:
Based on these first two images, it wold seem that a vent on the upper portion of the wheel well might have a larger impact on the vortex coming off the tire... decrease in drag? Lower vent would be more in line with equalizing pressure zones (downforce/lift). Or I could have that backwards for all I know.
And a diagram I had on my computer from a long time ago:
Hope this helps someone
~C