RÉSUMÉ

Algebraic relations that link the scalar-flux components to mean scalar gradient were investigated in several complex turbulent flows with impingement and separation. To illustrate the characteristics of the models, three flow configurations were selected, i.e., a fully-developed plane channel flow, a plane impinging jet and a separated flow around an obstacle in a plane channel, for all of which LES data were available for comparison as wall as for a priori test.
Previous studies have pointed out that higher turbulent Prandtl number or similar effect needs to be incorporated into the models for reasonable scalar-transfer predictions in the regions around stagnation and reattachment points. Such treatments commonly have the capability of reducing an excessive turbulent length scale for the scalar-field prediction.
The present investigations, however, indicate that model constants at the same level as in the channel-flow case may be used for predicting scalar fluxes even in complex turbulence with impingement and separation.