Heat transfer in a vertical rectangular duct filled with a porous matrix and saturated with a nanofluid for temperature dependent viscosity

Abstract

This paper presents the results of a comprehensive numerical study to analyze free convective heat transfer in a vertical  rectangular duct filled with porous matrix and saturated with nanofluid for temperature dependent viscosity. Using the Darcy- Forchhiemer model, the momentum in the porous medium was simulated. While  insulating two opposing wall ducts, the  temperatures remained varied for the other two walls. Solutions to the transport equations for a Newtonian fluid were provided
numerically through the finite difference approach to second order accuracy. The impact of the overriding parameters, for  instance, the parameters of variable viscosity as well as inertial, the Grashof number, Darcy number, Brinkman number, solid volume index as well as the aspect ratio having a water-Copper nanofluid on the flow characteristics of natural convection is investigated. The flow nature using different nanoparticles is also studied. The values of volumetric flow rate, skin friction and Nusselt number are tabulated for pertinent parameters. It is found that for negative values of viscosity variation parameter the flow is enhanced in the lower part of the duct and positive values will enhance the flow in the upper part of the duct. Silver nanoparticle attains the maximum heat transfer rate when compared to other nanoparticles.

Keywords: Natural convection; Darcy-Forchhiemer model; Nanofluids; Variable viscosity; Viscous dissipation; Rectangular duct; Finite difference method.