Quote:
Originally Posted by GenKreton
If you are familiar with Similitude and Buckingham Pi then this equation is trivial to develop (if you would like me to derive it, I shall):
Drag = (w/w_m)^2([rho]/[rho]_m)(V/V_m)^2 [Drag]_m
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I might have been familiar with it, but forgotten about it in non-use. But looking at it now I would suggest the following changes:
Drag = (S/S_m)*(rho/rho_m)*((V/Vm)^2)*Drag_m
Where S = area (cross-sectional or planform depending on body), rho = density, V = velocity, Drag = resistive force. However this is only true if Cdo == Cdo_m, which is not entirely true. A better example would be:
Drag = (S/S_m)*(rho/rho_m)*((V/Vm)^2)*(Cdo/Cdo_m)*Drag_m
Cdo and Cdo_m would need to be collected either from wind tunnel testing or CFD, and they definitely are a function of Re.