A New Rough Wall Layer Modeling Using the Brinkman Equation in Turbulent Boundary Layers

A new flow physics-based surface roughness model is developed for RANS (Reynolds averaged Navier-Stokes) numerical calculations of high Reynolds number turbulent flows over rough walls. In the proposed approach, the fluid dynamics of the volume-averaged flow in the near-wall rough layer is modeled by using the Brinkman equation. The porosity can be calculated based on the volumetric characteristics of the roughness and the permeability is modeled. The RANS equations are solved numerically above the near-wall rough layer, while a low-Reynolds-number k-e model is employed through out the whole domain. The computational results, including the skin friction coefficient, the log-law mean velocity profile, the roughness function, the turbulent kinetic energy, and the Reynolds shear stress are presented. The results show that the new rough wall layer modeling approach predicts well the skin friction coefficient, the log-law mean velocity, the roughness function, and the Reynolds shear stress.