Mixed convection in an open lid-driven cavity attached with a rectangular channel

Abstract

In this study, a numerical simulation is carried out investigation the mixed convection in an open lid _driven wall cavity attached to the horizontal rectangular channel. Three different cases were considered depending on the direction of moving the sidewalls of the cavity. In case(1), no moving walls were assumed ; While for case (case 2) the left sidewall of the cavity moves downward, in case (case3) both the left and right walls of cavity are moving downward. A comparative case( case1) is accounted when both side hand walls of the cavity are considered stationary. The heat source with the length of (ε=1) which is located on the bottom wall of the cavity and maintained at a constant temperature. The working fluid is air with a cold temperature and fixed velocity entered the channel horizontally. All the other walls of the channel and the cavity are adiabatic. A finite element method by used COMSOL Modelling Software is used to solve the governing equations.The simulation is carried out for study the effects of the Richardson numbers (Ri=0.1-100) with the movement sidewalls of the cavity, Reynolds numbers ratio(Rer=1-5) and aspect ratio(AR=1-2).The results were presented in the form of the contours of velocity and isothermal, average Nusselt numbers that, the downward movement of the sidewalls leads to accelerate the fluid to pass over the hot source with carried more energy and thus leads to increase in (Nuav) and improves heat transfer in a lid-driven cavity.The maximum value of the verage Nusselt number (Nuav) at (Ri=100) for all considered cases. Also, it was found, that (AR) has a significant impact on the flow and temperature fields that are achieved.