Assessment of non-Fickian subgrid-scale models for passive scalar in a channel flow

In order to assess new subgrid‐scale (SGS) models for a passive scalar, several large eddy simulations of a turbulent channel flow with passive scalar, for various Prandtl numbers ranging from 0.1 to 2.0 are carried out. These models are not based on the classical Fickian approximation and do not necessarily induce an alignment between the SGS heat flux vector and the gradient of the resolved temperature. Five SGS models are investigated on two grids. To validate the simulations, statistical quantities such as mean temperature, temperature variance and turbulent heat flux are compared with available data obtained by direct numerical simulation (DNS). The SGS dissipation is computed for different models in order to analyse its behaviour. The turbulence structures based on instantaneous velocity and temperature are described to study the correlations between these two fields. Among the assessed models, those consisting in Fickian and non‐Fickian parts seem to be full of promise. Copyright © 2005 John Wiley & Sons, Ltd.