Quote:
Originally Posted by aerohead
Characteristic 'length' for automobiles is derived from frontal area.
|
I suppose you could make an argument that frontal area and length are correlated, but even that is only generally true. Take a car like the Smart Fortwo (A = 21.0 square feet) and the original Honda Insight (A = 19.8 square feet) and it falls apart; the Smart is only 106" long while the Honda is 155".
In vehicle aerodynamics we're restricting Reynolds number calculations to incompressible flow; once you introduce things like compressibility and heat flux there are many, many other ways to calculate it. Perhaps you're thinking of one of those?