The relationship between the base pressure on a bluff body and the velocity at separation

In the modified free-streamline theory for the separated flow past bluff bodies due to Roshko, the velocity on the separated free streamlines is expressed as Uv=kU0 , where U0 is the velocity of the undisturbed stream and k is a constant. If it is assumed that the pressure on the base of the body is uniform and equal to the pressure on the free streamline, then application of Bernoulli's equation leads to; k =(1-Cpb)½,… (1) where Cpb is the base pressure coefficient.