A grid and flow adaptive wall-function method for RANS turbulence modelling

Abstract

This paper presents a grid and flow adaptive wall-function method for RANS turbulence modelling with emphasis on aerodynamic flows. A near-wall grid adaptation technique ensures a locally appropriate resolution depending on both the near-wall flow physics to be captured and the range of validity of the wall-function model. The near-wall RANS solutions of the Spalart-Allmaras and SST k-omega turbulence model are investigated near stagnation points and subsequent not yet fully developed turbulent flow, and in regions of adverse pressure gradient before separation. These are compared with the corresponding turbulence model specific universal wall-functions and suggestions for the design of wall-function methods for non-equilibrium flows are given. Regions of non-equilibrium flow are detected by a flow based sensor and near-wall grid adaptation is then made possible due to the hybrid character of the wall-functions.