Effect of temperature-dependent thermophysical properties on turbulent forced convection under constant heat flux boundary condition

TL;DR

This study uses high-resolution LES to examine how temperature-dependent fluid properties influence turbulent forced convection in a channel with constant heat flux, revealing minor effects on mean profiles but notable impacts on turbulence structures.

Contribution

It provides new insights into the effects of variable thermophysical properties on turbulence characteristics under constant heat flux conditions using detailed LES simulations.

Findings

Variable properties have trivial effects on mean velocity and temperature profiles.

Turbulence intensities and flow structures are significantly affected by property variations.

Classic wall scaling remains valid for flows with small to moderate property variations.

Abstract

In this study, we performed highly resolved large-eddy simulations (LES) to investigate the influence of variable properties on the forced turbulent convection in a channel. The constant heat flux boundary condition permits wall temperature fluctuations and thus induces variations of fluid properties. Since the effect of viscosity on the flow exhibits $Re_\tau^{-1}$ scaling, we only considered $Re_\tau = 180$ in the present study. Compared to the flow with constant properties, results indicate that the variable properties have trivial effects on the mean velocity and temperature profiles, Reynolds shear stress, wall-normal heat flux, as well as the small-scale turbulence characteristics. However, we also observed that the turbulence intensities, low-speed streaks, burst motions, and budgets for temperature variance and wall-normal heat flux are modified by the variable properties in a perceptible way. In addition, we showed that the classic wall scaling is a good choice for flow with small and moderate variations of fluid properties.