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Old 05-29-2011, 07:24 AM   #1 (permalink)
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Stepped shape for flow attachment.


I had a brainwave for a passive way of flow attachement with a great angle;
Letting flow stay attached over a surface passively about 17*degrees is the maximum.
Therefor a boattail has to be very long, then I thought of a the way a prius etc. uses a sharp leading edge for clean seperation of the flow.
Vortexes form becouse of the low pressure behind the car.
Vortexes can also be used for sucking in reattaching flow.
Thus a stepped slope would reattach the flow by creating small vortexes.
Then I searched on the web and found some interesting things.

A CFD simulation
323Ci Header/Full Exhaust/CAI/Chipped/3.46:1 Final Drive Build - Page 6 - E46Fanatics

Look at these race mirrors, implaying the same princible.

Look at this hungarian eco car, it's got a slopped rearwindow, exactly what i thougt of.

EU Transport Research-Fundamentals of Actively Controlled Flows with Trapped Vortices

Attachment browser: Fertis - New Airfoil.jpg by Dickeroo - RC Groups

I tried to simulate this with a CFD program on my computer, but as present don't see a change with a normal slope and a tepped one.

I would't love to have more info about this, imaging what's possible you could make a earodynamic side mirror or a rear window and still see enough through it.

Last edited by beer; 05-29-2011 at 07:36 AM..
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