Quote:
Originally Posted by vtec-e
So low hanging bumpers actually create a virtual rear bellypan then? The conventional wisdom here indicates that it acts as a parachute. Which makes sense. But so does the virtual bellypan.
Where have i gone wrong in my thinking? What am i missing?
ollie
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Ollie,imagine that the air captured within the boundary between both bumpers and the rocker panels just travels with the car.Like a pool of water upside down,with no influence from gravity.
If air WERE moving there,it would be like a literal torture-chamber for the air,with nothing but separated flow and mass quantities of turbulence.
By "capturing" air underneath there,all the air flowing below,will pass by undisturbed,with an un-obstructed path to the rear where it can inject it's kinetic energy into the wake to dilute it's drogue effect,That's where the drag is,behind the car.
If you cut a hole,now you've let the air out of the dam and re-opened the torture-chamber.And then there is the chance that ALL the air under the car will be turbulence,adding to the wake resulting in higher drag.