Question: A long right circular cylinder of diameter α m is set horizontally in a steady stream of velocity U m s-1 and caused to rotate at ω rad s-1. Obtain an expression in terms of ω and U for the ratio of the pressure difference between the top and bottom of the cylinder to the dynamic pressure of the stream. Describe briefly the behavior of the stagnation lines of such a system as ω increases from zero, keeping U constant.