Energy dissipation in a stably stratified thermally heterogeneous channel at a constant friction Reynolds number Reτ=395 and a molecular Prandtl number of Pr=0.71 is studied through a series of large-eddy simulations. The heterogeneity is varied by altering the aspect ratio (λ), while variation in the stratification level is achieved by altering the temperature ratio (ϕ) of the hot strip to the cold strip. The channel is homogeneous along the streamwise direction, and the thermal heterogeneity is incorporated along the spanwise direction. The effect of ϕ and λ on the turbulent kinetic energy distribution, temperature variance, and heat transfer mechanisms is analyzed at three regions of the channel, viz., near-wall (0y+62), intermediate (62y+190), and outer-layer region (190y+395), where y+ is the non-dimensionalized wall-normal distance. Component-level analysis is performed for the turbulent kinetic energy balance, temperature variance, and heat flux balance under varying ϕ and λ conditions to critically analyze the contribution of these mechanisms to the redistribution of total energy. The stratification and heterogeneity cease to influence fluctuation velocity components very close to the wall (y+20), while their implications are evident in the region y+≥20, extending to the center of the channel. Dissipation and viscous diffusion are stronger closer to the wall, with production countered by dissipation in the buffer layer region, which receives a substantial contribution from turbulent diffusion. A stronger stratification and heterogeneity have a greater depth of influence, extending to the intermediate region (62y+≤190) with an adverse effect on the temperature–pressure gradient correlation.
Bhaskar et al. (Fri,) studied this question.