Group buy on golf ball body kits?
#22
MR EG's taken fluid dynamics apparently!
The way I saw it, the dimples actually just create turbulence - causing a breakup of the pressure vaccum behind the car..
When a car passes through a fluid the car creates a giant pressure vaccum behind it. The vaccum is what i believe causes part of the speed limiting factor. The dimples break up the nice organized flow causing the pressure vaccum area to collapse much quicker behind the car, which results in less power needed to propel it forward.
~think of it as...a bullet through honey in slow mo. if you ever see it on youtube, you see the pocket of air behind the bullet. The pocket of air comes in with the bullet, but why doesnt the honey collapse totally on top of it as the bullet goes through? Its because the honey follows the streamline (lines of the BL that mrEG was talking about), which doesnt allow it to just drop and fill in the hole behind the bullet. The hole behind the bullet, has a really LOW pressure - pressure is inversely related to velocity - the faster a fluid flows, the lower the pressure (bernoulli [sp?]) so as a car goes faster, the pressure differential between the front of the car and the rear grow larger - pressure difference over area = force.
turbulence is usually a BAD thing - it takes more force to get turbulent flow to flow through a pipe than to get fluid to laminarly flow through a pipe...
I highly doubt the boundary layer will factor significantly into the power requirements since the fluid we are talking of is air. Also, a turbulent BL will usually require more force to get through (IIRC from my fluids/heat transfer classes).
The way I saw it, the dimples actually just create turbulence - causing a breakup of the pressure vaccum behind the car..
When a car passes through a fluid the car creates a giant pressure vaccum behind it. The vaccum is what i believe causes part of the speed limiting factor. The dimples break up the nice organized flow causing the pressure vaccum area to collapse much quicker behind the car, which results in less power needed to propel it forward.
~think of it as...a bullet through honey in slow mo. if you ever see it on youtube, you see the pocket of air behind the bullet. The pocket of air comes in with the bullet, but why doesnt the honey collapse totally on top of it as the bullet goes through? Its because the honey follows the streamline (lines of the BL that mrEG was talking about), which doesnt allow it to just drop and fill in the hole behind the bullet. The hole behind the bullet, has a really LOW pressure - pressure is inversely related to velocity - the faster a fluid flows, the lower the pressure (bernoulli [sp?]) so as a car goes faster, the pressure differential between the front of the car and the rear grow larger - pressure difference over area = force.
turbulence is usually a BAD thing - it takes more force to get turbulent flow to flow through a pipe than to get fluid to laminarly flow through a pipe...
I highly doubt the boundary layer will factor significantly into the power requirements since the fluid we are talking of is air. Also, a turbulent BL will usually require more force to get through (IIRC from my fluids/heat transfer classes).
#23
Originally Posted by Fapout,Oct 26 2009, 01:21 PM
A little bit... could use a happy ending though.
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