First of all, good luck with your blog Amouzouris!
I see you are using Wtunnel-Pro for iphone and ipad?
The CFD is not representative because the simulation tool is a toy. More on that later, but funny enough, I looked at the same issue with exactly the same tool (toy) a few days ago.
If you want to extract anything from that tool, you'll have to keep things very, very simple. More like this:
Symmetrical nose, no downforce (there is some lift as I didn't get the shape exactly symmetrical).
Add the bulge, some downforce. The pressure distribution is clear.
The way I see it, that bulge is like a wing profile but without the rear part pointy end. It will create a bit of downforce by itself. Being between the nose pylons, it will also have the effect of a Venturi channel. What it won't have is the upwash of a wing, as the bodywork behind it prevents this from happening to a large extent.
So there are two possible advantages. One is downforce free of upwash induced drag. The other one, as you mentioned, is conditioning the flow behind.
The downside of course is some obstruction of air to the back of the car.
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Now as to why you should be very, very, VERY cautious using this Wtunnel-pro tool:
1) It is 2D, obviously. That still should allow it to be good enough for some concept tests like this.
2) From the web page of the tool:
What are the units of the simulation ?
There are currently no actual units in the simulation. It was at first designed to be a visual app, not an engineering tool. However, we agree it could be interesting to give some units and values (speed, viscosity, pressure, Reynolds number). We are working on it and might include some units in a future update.
This means that we don't know if the density, viscosity, etc. is equivalent to those of air, water or molten lava.
3)
The velocity field is solved in a 120ร160 grid on iPad and on a 92ร138 grid on iPod/iPhones.
This means that models have to be insanely simple.
4)
...we developed a highly optimized simulation engine...
I am not sure how to interpret that, but my first instinct is that they simplified the math. That's never a good idea and the tool does display some really bizarre behavior. Particles stick to the walls and flow separation is moody, but the worse is that the conservation of mass is somehow broken. Simulations like this show it clearly:
The straight lines are velocity field, the dots simulated particles. As one can see, they go into the bottle and keep entering and entering for ever and making a whirlwind), yet nothing comes out. Whatever simplification they did, it was a step too far.
So be very, very, very careful before concluding anything from this tool!
Rivals, not enemies.