Fluid flow and heat transfer in microchannel with and without porous medium under constant heat flux

In this study, the heat transfer and fluid flow characteristics of a three-dimensional microchannel that is partially filled with a layer of porous medium at its bottom solid wall is investigated. The microchannel is consisted of a clear fluid flow region, solid walls and a porous layer that is attached to its solid bottom wall. A constant heat flux is applied to the bottom wall of the microchannel. Darcy-Brinkman-Forchheimer model is used to simulate the fluid flow inside the porous medium. The novelty of this work is to investigate thoroughly and precisely the effect of using of porous layer configuration in MCHSs on hydraulic and thermal performances. The effect of porous layer thickness, permeability, porosity, and the mass flow rate on the flow field characteristics and heat transfer performance of the microchannel are examined for the dimensionless porous layer thicknesses δt=0,2,4,6,8,and10\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{\delta }{t} = 0, 2, 4, 6, 8, \,{\text{and}}\,10$$\end{document}. For porous characteristics of K=10-7m2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$K = 10^{ - 7} \,{\text{m}}^{2}$$\end{document} and ε=0.6\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon = 0.6$$\end{document}, the microchannel with dimensionless porous layer thicknesses of δt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{\delta }{t}$$\end{document} = 2, 4, 6, 8 and 10 have the pressure drop of 1.47, 1.78, 2.11, 2.49, and 2.93 times greater than the microchannel without porous medium respectively. Simultaneously, they have Nusselt number of 1.64, 1.69, 1.75, 1.82 and 1.9 greater than the microchannel without the porous medium respectively. In addition, by increasing of porosity and permeability, the fluid velocity inside the clear region increases, while the fluid velocity inside the porous region decreases, which can be utilized to explain the increase of pressure gradient and Nusselt number.