shelly wrote:Some months ago I thought too that the strakes crated two counterrotating vortices for the exhaust to flow between them; but after looking at more rb9 pictures I think now that the exhaust flow to the inside of the inner strake and that the double strake's purpose is to create a more complex vortex structure made up of two corotating vortices.
Difficult to say because the airflow in front of the tyre will be not very clean.
Looking at the shape of the two strakes I think they want to create (similar to RB) a big Vortex around the exhaust flow. The sense of rotation of this vortex would be opposite to the footplate vortex and above it thereby stabilising it and keeping it from being sucked into the diffuser (similar to meteorology where a neighbouring high and low pressure area will stabilise each other and link them together by counter- rotating)).
The shapeof the inner seems to suggest the the vortex should detach toward the inside of the car, but eye-guessing is too poor an analysis tool
Yep, exactly that is what I assume as well. If my assumption is correct the outer strake is just used to properly push/direct the air (displaced by the tyres) over the inner strake (which seems to have toe-in) and create local high pressure between the strakes, thereby initiating a vortex which is rotating clockwise (left side of the car) when seen from behind and counter- clockwise on the right side of the car, respectively.