Experimental and numerical natural convection in an asymmetrically heated double vertical facade

Abstract

The present work addresses the numerical and experimental study of natural convection inside an asymmetrically heated open double vertical facade. Two heating cases were considered independently, the constant heat flux (Neumann condition) and the constant temperature (Dirichlet condition). The double facade has been modeled using a vertical two-dimensional channel with one wall being maintained at the heating condition and the other one insulated. The boundary conditions at the inlet and outlet were controlled through the addition of adiabatic walls upstream and downstream of the studied area. The airflow is assumed to be laminar and permanent. This study is conducted for several modified Rayleigh numbers ranging from 102 ≤ Ram ≤107 and different aspect ratios (A = 25, 12.5, 8.34, 6.25, and 5). Various parameters have been evaluated and highlighted, namely velocity and temperature profiles. In the first part of this study, the radiative heat transfer is not considered, comparison results give excellent agreement with the experimental work of Webb and Hill [18]. Similarly, the streamline results show a return flow through the outlet of the channel starting from a modified Raleigh value of Ram = 104.In the second case of this study and for isothermal conditions, the radiative transfer is taken into account with mutual radiative heat exchanges between the surfaces and for a transparent not participating medium. The comparison results between the experimental and numerical heat fluxes along the heated plate gives a very good agreement, as well as for the mean Nusselt values for 2.28 × 102≤Ram≤8.22 × 105.