Effect of viscous dissipation on mixed convection flow of water near its density maximum in a rectangular enclosure with isothermal wall

Abstract

PurposeTo investigate the effect of viscous dissipation on unsteady, combined convective heat transfer to water near its density maximum in a rectangular cavity.Design/methodology/approachThe upwind finite difference scheme along with successive over relaxation iteration technique is used to solve the governing equations for mixed convection flow of water with density maximum inversion in a rectangular cavity.FindingsThe effect of viscous dissipation was to increase the fluid temperature and resulted in the formation of vortex motion near the lower part of the cavity in an opposite direction to the central vortex. An increase in the Eckert number and Reynolds number of the flow resulted in augmented surface heat transfer rates from the top heated surface.Research limitations/implicationThe analysis is valid for unsteady, two dimensional laminar flow. Isothermal conditions are assumed for the top and bottom walls. An extension to unsteady three dimensional flow case is left for future work.Practical implicationsThe method is very useful to analyze nuclear reactor thermal/hydraulic loss of coolant transients, energy conservation, ventilation of rooms, solar energy collection, cooling of electronic equipment, dispersion of waste heat in estuaries and crystal growth in liquids.Originality/valueThe results of this study may be of interest to engineers interested in heat transfer augmentation of mixed convection in window cavities.