Prediction of turbulent skin friction for two-dimensional, rib-type surface roughness using a discrete element approach.

A discrete element model for turbulent flow over two dimensional rib type roughness is presented. This formulation includes surface roughness form drag and blockage effects as a constituent part of the differential equations. Predictions are compared with a variety of data sets. These comparisons indicate that the discrete element approach can be successfully applied for rib type roughness. However, the model has a more narrow range of application for different surface geometries than the very broad range which has previously been demonstrated for three dimensional, distributed roughness. (A)