A discrete element prediction approach for turbulent flow over rough surfaces

A discrete element model for turbulent flow over rough surfaces was rigorously derived from basic principles. This model includes surface roughness effects as a constituent part of the partial differential equations which describe momentum and energy transport in turbulent flows. The model includes the necessary empirical information on the interaction between the roughness elements and the flow around and between the elements in a general way which does not require experimental data on each specific surface. This empirical information is input via algebraic models for the local element drag coefficient and Nusselt number. These models are calibrated by comparison with base data sets from surfaces with three-dimensional (distributed) roughness elements.