So, in what I guess is probably going to be the final step of our little collaboration I thought I would do a final analysis of the CFD. (Again, this is presented for Newbies and not directly at you guys!)
The two main areas as discussed before I think are the diffuser and the flow in the middle of the car.
The flow in the diffuser area is showing the effects of the entrainment of the rear wheel contact patch wake (I've exaggerated the blue area on the velocity plot for clarity, see below). This low velocity "cloud" spreads out and starts to "take over" the diffuser. I've found that adding diffuser strakes can help to control the spread of that low velocity "cloud" and increase downforce and decrease drag... so this might be something to have a play with amongst others.
In front of the side-pod side there is still that area of recirculation. Maybe you should try your/Wesley's idea to extend the front suspension fairing to enclose the side-impact structure to further prevent this air moving vertically and direct it through this area and out of the sides of the car instead, and I think you can improve the leading edge of the floor as well: remember air doesn't like flowing across a "sharp" object: it just detaches...
Once you've had a play with those (and other aspects of the diffuser, such as different expansion ratios, different angles, etc) then you're down to looking at small areas of the body to look for improvements. As we said before: you're looking for low pressure areas on top and back of the body which manifest themselves as areas of lift and drag.
On the images below I've marked on the direction of the resultant forces due to the surface pressures (These are just perpendicular to the surface): anything pointing vaguely backwards is creating drag and upwards is causing lift. I don't think there is a huge amount to be gained here, but maybe a few modifications to the tops of the wheel fairings could be tried; remember you're trying to avoid downward curving surfaces... sometime purposely causing the air to separate from the bodywork can be of benefit (i.e. so the air doesn't follow the downward curving bodywork and create lift).
You may also want to try changing things like slot gaps and wing element profiles, although yours seem to be working quite well...
Also remember that any gains in Downforce at one end need to be balanced with more downforce at the other end...
And finally: best try one thing at a time so you can be sure how each change has affected the car...
I'm sure we all look forward to following your car development further so keep us posted on your thread!
