On the Wake and Drag of Bluff Bodies

A modification to Kirchhoff's free streamline introduces the parameter k = √(1- C_ps), which allows arbitrary base pressure and which must depend on the dynamics of the wake. For a cylinder of given cross-sectional shape, the drag, C_D, and the wake width, d', are functions of k only. These functions are used to relate C_D and the dimensionless shedding frequency , S = nd/U_ ∞ to another number, S* = nd' / U_s, which is based on wake parameters. It is found that S* = 0.16 for all cylinders. In another approach, k is evaluated by using Karman's solution for the vortex street.