Thanks! - Jahee

Happy to hear it helps!

Thanks for the kind words.. Well all other things equal i.e an equal area of flat floor upstream the substantial differences vs. The arrangement discussed here are that most flat floored race cars will have: 1. A front diffuser 2. 4 wheels influencing flow across the entire underbody 3. Depending on the car type, a rear wing close enough that it’s affecting the flow field in the divergent section In very short summary, the front diffuser will affect the quality of flow travelling to the divergent section in terms of turbulence and mass flow, each of the 4 wheels will kick out a fairly substantial volume of air towards the centre of the car, again negatively influencing the flow quality at different points of the underbody. The rear wing can also be positioned (look at Group C cars for reference) adjacent to the flow leaving the underbody where the low pressure field underneath the wing will act as an extractor - drawing a larger volume of air under the car and also helping the flow in the divergent section to stay attached. Interesting stuff! I welcome any follow up questions if you have them - Jahee

Thanks! I briefly explored (in CFD) a couple of techniques to test the same theory actually but after the initial results weren't promising i moved on. The benefit of having them by the shoulder is that the flow exposed to the diffuser section is travelling upwards - If you have the wrong side of the vortex exposed as well, you're not only drawing air upwards, but also drawing it downwards on the other side, the net effect is a loss - especially as any flow device used to generate the vortex messes up the flow upstream too..!