DNS and LES of turbulent channel flows with temperature-dependent variable viscosity*

Modification of turbulence by temperature-dependent fluid properties is significant in high Prandtl number flows with relatively large temperature differences. The present DNS study describes how large the turbulence and turbulent scalar fields are modified by the temperature-dependent viscosity in a water channel flow at Ret=650. The present study also has performed an LES and discusses the importance of including the correlation term between velocity and variable viscosity. A comparison between the DNS and the LES data suggests that although the effects of the velocity-variable viscosity correlation term is not totally ignorable, the LES without such a term can capture most of the essential characteristics of variable viscosity turbulence. The present study also provides a database for the velocity-variable viscosity correlation term to discuss its modelling.