Open Access

ARTICLE

Mixed Convection of a Nanofluid in a Vertical Anisotropic Porous Channel with Heated/Cooled Walls

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1 Faculty of Mechanical and Process Engineering, Houari Boumediene University of Sciences and Technology (USTHB), B. P. 32, El Alia, Bab Ezzouar 16111, Algiers-Algeria

Fluid Dynamics & Materials Processing 2017, 13(3), 155-172. https://doi.org/10.3970/fdmp.2017.013.155

Abstract

A numerical study is conducted to investigate the problem of mixed convection of a nanofluid in a vertical porous channel with one wall heated and the other cooled. The Darcy-Brinkman-Forchheimer model is used to describe the flow in the porous medium, considered as anisotropic in thermal conductivity, and the two-phase approach is adopted to simulate the motion of the nanofluid. The governing equations with the associated boundary conditions are solved by the finite volume method. The parametric study is focused on the variation of the Richardson number Ri, the heat fluxes ratio R_q, the Darcy number and the thermal conductivity ratio λ characterizing the anisotropy. The results revealed that the heat transfer rates for both channel walls increase with λ and decrease with Da. The mean Nusselt number for the heated wall increases with the rise of Ri and R_q, while that for the cooled wall evolves in opposite direction. In addition, it is found that the dynamical and thermal fields become extremely sensitive to the variations of the various parameters mentioned above when reverse flow appears. For this reason, maps showing the situations of occurrence of this phenomenon are performed.

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Keywords

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