Ben Diss;214906 Wrote: > Sorry, guys. I gotta call a BS on this. A rough surface increases > drag. Dimples and other effects that control vortices can improve > performance by managing air separation over the surface. On airplanes, > we use vortex generators to do this. Dirt on a car or airplane slow it > down. I once read a CAFE study that tried to determine the performance > impact of waxing an airplane. They concluded there was none, but > discovered about a 1% increase in top speed by removing bugs and dirt > from all surfaces. > > -Ben
Rough surfaces increase drag *at the surface*, but they also can create a turbulent layer of air at relatively low speeds. The main flow slipping around that layer can then remain laminar for longer and close in more tightly behind the object, which sometimes means that the overall drag is reduced. My intuition on a piece of dirt on an airplane is that it probably would slow it down, because one or a few pieces of dirt are not going to create such a layer. But if you really dipped it in mud or something, who knows... Exactly what happens in some particular case is extremely difficult to predict: http://www.claymath.org/millennium/Navier-Stokes_Equations/ -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=36854 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
