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Coefficient of drag as a function of Reynolds number

Coefficient of drag as a function of Reynolds number
Coefficient of drag as a function of Reynolds number Coefficient of drag (y-axis) as a function of Reynolds number (x-axis). Reynolds number is a dimensionless ratio that characterizes fluid flow. In this case it is the velocity of the rock times its diameter divided by the kinematic viscosity of the air. The sudden drop in drag that occurs between Reynolds numbers of 105 and 106 is the “drag catastrophe”.