opaqueice;214909 Wrote: > 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/
Controlling turbulence at the boundary layer may allow the flow to remain attached longer, but it will not cause it to be a laminar flow and it will not reduce overall drag. For example, adding vortex generators to an airplane will aid in control as the airflow remains attached at the control surface, but the penalty is lower max airspeed. -Ben -- Ben Diss 'SB3' (http://www.slimdevices.com/pi_squeezebox.html) -> 'Lavry DA10' (http://www.lavryengineering.com/productspage_da_10.html) -> 'BAT VK-31SE' (http://www.balanced.com/products/line/Vk-31SE/index.html) -> 'Halo A21' (http://www.parasound.com/halo/a21.php) -> 'B&W 803D' (http://www.bwspeakers.com/index.cfm/fuseaction/products.models/label/Model%20803D) ------------------------------------------------------------------------ Ben Diss's Profile: http://forums.slimdevices.com/member.php?userid=4289 View this thread: http://forums.slimdevices.com/showthread.php?t=36854 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
