Bearfoil,
I have to admit I always had difficulties with the circulation model at AoA = 0 for an asymmetrical foil like e.g. NACA4312.
It's clear if we have a high AoA where the air on the lower side is decellerated. In that case we get a flow around the TE which tries to 'fill the void'.
To stay in your very nice example like in real life the molecules want to have equal space around them. I.e. they alway try to go there where the density is lower, i.e. where there seems to be a void.
That is what you see in animations of the circulation model.
If you now take a semi- symmetrical Profile at Alpha = 0, you don't have a decelleration. You only have less acceleration on the lower side than on the upper side. And that is a case where I don't really see a significant equalising flow from Upper to lower side at the TE. I see more or less just the added vertical speed component which gives the Newton Part of the Lift.
From my point of view the circulation only becomes really relevant at certain AoA. For very low AoA I tend to consider in negligeable,
Would be interesting to make such a simulation in coloured water for different AoA's to see when the effect really kicks in.
Very interesting discussion !
Thanks for the thread !
regards,
henra