Numerical investigation of mixed convection of nanofluid flow in a trapezoidal channel with different aspect ratios in the presence of porous medium

Abstract

In this study, a numerical investigation of mixed convection of nanofluid flow in a trapezoidal channel with two different aspect ratios of 0.3 and 0.5 with the presence of porous media is investigated. The present study was based on Ri = 0.1, 1, and 10 and used water-Al2O3 nanofluid in ϕ= 0–3% as the working fluid. Also, metal foam made of aluminum alloy in Darcy numbers 10−2, 10−3, and 10−4 is used for the porous medium, and the thermal equilibrium model is used to simulate the porous medium. The finite volume method and the single-phase model are applied. Nusselt number diagrams for different porous heights are obtained in different Darcy and Richardson numbers for the lower and upper walls of the channel. The results show that with the decrease in Richardson number, the local and NuAveincreases. In addition, a fully filled channel with a porous medium does not yield satisfactory results for the lower wall, but the results are desirable for the upper wall. The highest heat transfer occurs in the 90% porous height range. Aspect ratio of 0.3 predicts more heat transfer than aspect ratio of 0.5. As the height of the porous medium increases, the NuAve goes through an upward-downward trend, with two heights of 10% and 90% of the turning points in this upward and downward trend. As the percentage of porous height increases, the Darcy number changes on the heat transfer rate exhibit unique behaviors.