Impact of Prandtl numbers on turbulence modeling

Abstract

A low-Reynolds number (LRN) k-ϵ turbulence model is devised that includes the near-wall turbulence modeling and turbulent Prandtl numbers σ(k,ϵ,t). A secondary source term added in the ϵ-equation accounts substantially for the anisotropic production in near-wall regions. Hence, improved predictions of adverse pressure-gradient flows, involving separation and reattachment are obtained with a considerable reduction in the turbulent kinetic energy and length scale magnitudes. The eddy-viscosity formulation responds to both rotational and irrotational strains to better predict nonequilibrium flows. The current model employs no wall function/distance parameter to bridge the near-wall integration as required by conventional k-ϵ models. Model predictions are compared with direct numerical simulation (DNS) and experimental data; a good correlation is achieved.