ISSN Online: 2377-424X
International Heat Transfer Conference 12
WALL-FUNCTION STRATEGIES FOR USE IN TURBULENT FLOW CFD
Abstract
For CFD calculations of turbulent flow near smooth walls, two broad strategies are used to resolve the very influential, very complex and very thin near-wall viscosity-affected sub-layer. Either one uses a fine numerical mesh and a turbulence model that (supposedly) accounts for viscous influences; or one employs "wall functions" − overall formulae that attempt to take account of the resistance of the sublayer to the transport of momentum and heat. The latter may require only one-hundredth of the computational effort of the former and are thus strongly favoured for industrial calculations. The track record of such schemes is poor, however, partly because of inappropriate implementation and partly because the schemes themselves have inherent limitations.
The present paper reviews the evolution of wall-function strategies since the 1960's. Attention is then given to two new schemes evolved by the authors, one based on an analytical treatment and the other on a numerical resolution of the near-wall sub-layer. Several recent applications are shown of mixed and forced convection.
The present paper reviews the evolution of wall-function strategies since the 1960's. Attention is then given to two new schemes evolved by the authors, one based on an analytical treatment and the other on a numerical resolution of the near-wall sub-layer. Several recent applications are shown of mixed and forced convection.