Numerical modelling of turbulent flow over rough walls

Abstract

The numerical simulation of turbulent flow over rough walls was carried out for various types of roughness. The mathematical model was based on the Reynolds averaged Navier-Stokes equations for incompressible flow. The two-equation SST and oneequation Spalart-Allmaras turbulence models were used. Boundary conditions on rough walls were prescribed directly on the wall using the SST model modified to account for wall roughness by Hellsten and Laine (1997) and the SA model modified by Aupoix and Spalart (2003). Turbulence models were tested for the constant pressure turbulent boundary layer on the rough wall formed by commercial abrasive paper and by tightly packed spheres. The effect of wall roughness on the decelerated flow over a smoothly contoured ramp with flow separation was investigated. Obtained results were compared with experimental data.

A CFD study: Influence of biofouling on a full-scale submarine

“…Thus, it can be efficiently modelled with the Reynolds-Averaged Navier-Stokes (RANS) equations with the full resolution of time-averaged near-wall flow without incorporating the wall functions. Although there were studies including numerical methods to investigate the effect of a rough surface on the flow [39], [40], [41], [42], [43], [44] none of them was interested in investigating the roughness effect with RANS. Therefore, Eca and Hoekstra [38] modelled sand-grain roughness in the shear stress transport (SST) of the eddyviscosity k-ω turbulence model by using three types of implementation.…”