Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Abstract

The objective of this work is the mathematical modelling and the numerical simulation of the stationary, laminar, and natural convection, in a confined square cavity (H = L) filled with two fluids (a mixture of nanoparticles of aluminum oxide and Al2O3 water) in one partition and pure water in the other partition. A porous conductive wall of thickness w (w = L/e) and thermal conductivity Keff constitutes the exchange surface between these two partitions. The fluid movement is modeled by the Navier-Stokes equations in the two partitions, while the porous medium is modelled by the Darcy–Brinkman equation. Comsol Multiphysics software is used to solve the system of differential equations that is based on the finite element method. The results are discussed with particular attention to the mean and local Nusselt number (Nu), streamlines and isotherms. A parametric study for Rayleigh number Ra (102 to 106), volume fraction j (0% to 10%), and Darcy number Da (10-7 to 10-2) is performed. The obtained findings show that the increase in Ra, Da, and j intensifies the flow and improves the thermal exchange on the cold wall. For Da £ 10-5, Nu remains practically low and the natural convection is being dominated by conduction. For Da > 10-5, an increase in Nu is observed and the flows tend towards a purely convective situation. Furthermore, an increase in the heat transfer coefficients is observed with the raise of the porous layer permeability, volume fraction and Rayleigh number.

Effect of Magnetic Field on the Developing Thermal Field in a Duct Filled with Porous Media under Local Thermal Non-Equilibrium with a Nonlinear Flow Model

“…In Eq. ( 3) to ( 5), Da, M, F, and Bi denote the Darcy number, Hartman number, Forchheimer number, and Biot number, respectively [32][33][34][35][36][37]; however, ε, k1 and, κ represent the ratio between the viscosity of the fluid to the effective viscosity of the porous, fluid thermal conductivity to porous thermal conductivity, effective solid thermal conductivity to effective fluid thermal conductivity in the porous region, respectively and it can be defined as…”

Unsteady Natural Convection in a Porous Square Cavity Saturated by Nanofluid Using Buongiorno Model: Variable Permeability Effect on Homogeneous Porous Medium

“…The importance of the application of nanofluide in porous medium received a great attention by many authors such heat exchangers [34], electronic cooling and solar system, according to the studies the use of both and nanofluide and porous media can enhance the efficiency of typical thermal systems, a mixed convection flow in a boundary layer saturated by a nanofluid and lodged in a porous medium have been studied by Abu Bakar et al, [35]. , Douha et al, [36] have proved that an increase in the heat transfer coefficients is observed with the raise of the porous layer permeability.…”

Effect of the position of the hot source on mixed convection in a rectangular cavity

“…In general, several scientific researchers have studied flow dynamics and heat transfer in both two and three-dimensional [1]- [4] configurations in various geometric shapes [5]- [14].Due to its high performance and limited energy demand, a study of laminar mixed convection cooling of a rectangular cavity with a constant source of heat flow was the subject of [15]to identify optimum location of inlet and outlet for better cooling efficiency. For various ventilation arrangements, free and forced convection was investigated in a rectangular enclosure with a source heated from below.…”