International Journal of Numerical Methods for Heat & Fluid Flow

Purpose – This paper sets out to perform a detailed numerical study of turbulent channel flow with strong temperature gradients using large-eddy simulations.

Design/methodology/approach – A recently developed time-accurate algorithm based on a predictor-corrector time integration scheme is used in the simulations. Spatial discretization is performed on a collocated grid system using a flux interpolation technique. This interpolation technique avoids the pressure odd-even decoupling problem that is typically encountered in collocated grids. The eddy viscosity is calculated with the extension of the dynamic Smagorinsky model to variable-density flows.

Findings – The mean velocity profile at the cold side deviates from the classical isothermal logarithmic law of the wall. Nonetheless, at the hot side, there is a better agreement between the present results and the isothermal law of the wall. Further, the numerical study predicts that the turbulence kinetic energy near the cold wall is higher than near the hot one. In other words heat addition tends to laminarize the channel flow. The temperature fluctuations were also higher in the vicinity of the cold wall, even though the peak of these fluctuations occurs at the side of the hot wall.

Practical implications – The findings of the paper have applications in the design and analysis of convective heat transfer equipment such as heat exchangers and cooling systems of nuclear reactors.

Originality/value – The paper presents the first numerical results for non-isothermal turbulent channel flow with high wall-temperature ratios (up to 9). These findings can be of interest to scientists carrying out research in turbulent flows.