Quote:
Originally Posted by chillsworld
THANK YOU!
That first part was my main concern with the material. I would think that the boundary layer would be much thicker on the vehicle, and might require large dimples like those on the drift boat or surf board?
Also, point #2 of yours, the vortex/turbulators I have seen are generally at the point of detachment on the rear window, the ends or edge of the rear of the car. And as you said, require specific placement... That's why I had envisioned the non-uniform surface that carried over from the roof and rear pillars, keeping the flow attached rather than making vortexes to smooth unattached air. Like this... Concept car by French designer Dimitri Bez
Would that make sense? I mean I'm apparently noy the only person to think of this, since he already has a car using this idea lol
~C |
*There is only an inch or so of laminar boundary layer on a car.The rest is turbulent boundary layer.
*This TBL allows for attached flow as long as the body cross-section does not vary by much (area rule/sectional density).
*Once you have TBL there is no need of dimples,as they'd be superfluous and only increase drag.
*If you have contours on the car which are too 'fast',then a dimple might behave as a crude VG,but they are in no way as efficient as a true VG,as far as feeding momentum into a compromised TBL which is otherwise separating.
*It is the vortices created by VGs which feed momentum into the weak TBL,forestalling separation.
*Dimples cannot produce the quality of vortices as with VGs.They are very inefficient in this regard.
*The only reason golf balls have dimples instead of VGs is because the ball spins,and regardless of the balls orientation in the air,the dimples always present the same 'face' to the boundary layer,allowing predictable flight.
*If the ball could be oriented and struck with the driver or iron without imparting spin,then we could put VGs on them and extend a drive or chip shot.
*In water,the dimples would help the board or hull 'plane',as in a stepped hull.The curvature is too gentle to produce separation.
*I feel like Bez has not read Hucho or anyone else,and is clueless about boundary layer theory,otherwise he wouldn't have done what he's done.
*Same for Mythbusters.They must be an embarrassment to whoever authorized an engineering diploma.
*If any notchback car is going to be modified for boundary layer control,it should be done with VGs.It's just better science.