Study of mixed convection in a horizontal cylindrical pipe partially filled with a porous medium saturated with a single fluid

Abstract

The three-dimensional numerical simulation of laminar mixed convection heat transfer with and without porous medium in a cylindrical duct was carried out in this study. The cylinder is divided into three parts. The first and the third parts are adiabatic, while the central part is subjected to a constant heat flux. The effects of Darcy number, porosity, permeability and Nusselt number on heat transfer were considered. This problem is modeled by the Navier-stokes equations in the fluid region and by the Darcy-Brinkman-Forchheimer equation in the porous region, and for the thermal field the energy equation is used. The resolution of these equations was performed by the computational fluid dynamics code Ansys15.2 software using finite volume approach. The obtained results showed an accumulation of the hot fluid with stratification in the upper part of the pipe while the lower region of the pipe remained at practically constant temperature. The effect of the porous matrix is very noticeable on the velocity profile. The insertion of a porous high permeability medium significantly improves heat transfer.