Quote:
Originally Posted by Ian Curtis
I'm not sure what you're doing, but I'll readily admit my grasp on Boundary Layers isn't spectacular (one of those classes you can ride the curve to victory). Is that an assumed velocity profile? If it is I doubt it works, because the velocity profile varies with theta. Boundary Layers typically assumes small Re where you have nice laminar or creeping flow. Take a look at this .gif, on the backside the flow is going to seperate with a ball moving in air at any noticeable speed.
If it's one of those experimentally determined equations for Cd, then it is probably okay.
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Also... that's for a SMOOTH CYLINDER. Gets more complicated with a sphere, as you've added another dimension. Not to mention that the game pieces aren't smooth, they have little bumps which will cause the turbulent section of the boundary layer to engulf the entire ball... will reduce overall CD but increase effective aerodynamic diameter for all other calculations.
http://www.mcoscillator.com/data/cha...yer-sphere.jpg