Friction factor for flow past an infinite cylinder, the flow past a long cylinder is very different from the flow past a sphere, and the method introduced in S4.2 can-not be used to describe this system. It is found that, when the fluid approaches with a velocity v∞, the kinetic force acting on a length L of the cylinder is The Reynolds number is defined here as Re = Dv∞p/µ. Equation 6B.9-1 is valid only up to about Re = 1. In this range of Re, what is the formula for the friction factor as a function of the Reynolds number?