Validation of the thermal equilibrium assumption in periodic free convection in porous channel using Darcy-Brinkman Forchheimer model

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Examination of the thermal equilibrium assumption in the periodic natural convection channel flow is investigated numerically. The periodic disturbance in the free convection flow is due to a periodic thermal disturbance imposed on the channel walls. The Darcy-Brinkman-Forchheimer model is used to describe the flow inside the porous channel. A scripted finite element model builder and numerical solver, FlexPDE, is used to solve the equations. Five dimensionless parameters are found to have significant effect on the local thermal equilibrium assumption. These parameters are thermal conductivity, volumetric Nusselt number, thermal diffusivity ratio, amplitude of thermal disturbance and frequency of the thermal disturbance. The effects of these parameters on the local thermal equilibrium assumption are investigated. The volumetric Nusselt number is found to have the most significant effect on this assumption.