Drag determination from mean velocity profiles in rough-wall boundary layers

A method for determining the friction velocity in wall bounded flows has been extended for use with rough surfaces. The original method (Dixit et al.) is applicable to smooth wall flows, and requires only the mean streamwise velocity profile at a single location. It does not rely on any assumptions about the shape of the profile, and is applicable in both zero and non-zero pressure gradients. The new method is the same as the original, with the exception that the kinematic viscosity is replaced with an effective viscosity that is proportional to the product of the roughness height and flow velocity.