Turbulent heat and mass transfer from a wall with parallel roughness ridges

Abstract

As it is known, the general equation for the coefficient of heat (or mass) transfer between a rough wall and a turbulent fluid flow can be derived with the aid of general dimensional and similarity considerations supplemented with some additional physical arguments. The equation is specified here for the case of a wall covered with two-dimensional roughness in the form of widely spaced parallel ridges perpendicular to the stream direction. The constant coefficients of the derived equation are approximately estimated from the available data on mean temperature or concentration profiles in wall turbulent flows over two-dimensional roughness. The final results of the calculations agree satisfactorily with all of the experimental data on turbulent heat and mass transfer in pipes and channels with regularly repeated parallel roughness ridges and in boundary layers on plates with two-dimensional roughness of the same form.