Mixed convection heat transfer from surface-mounted block heat sources in a horizontal channel with nanofluids

This paper presents laminar mixed convection flow of Al2O3/water nanofluids in a horizontal channel where two hot obstacles are mounted on the bottom wall. The governing equations are solved numerically using finite volume method and SIMPLER algorithm. Three thermophysical models including temperature-dependent and temperature-independent relations are selected for the study. The results are shown for a wide range of key parameters in the problem, i.e. Richardson number, Rayleigh number, and nanoparticles volume fraction. In addition, the effects of different aspect ratios of obstacles on average Nusselt number are examined. The findings elucidate that the difference between average Nusselt numbers obtained from the three sets of thermophysical models does not exceed 3%. The results also show that with increasing the nanofluid concentration from 0% to 5%, the average Nusselt number over the obstacles increases less than 10%.