Influence of active flow modulation on conjugate mixed convection inside a vented cavity

Abstract

The current work is an attempt to examine the performance of mixed convection heat transfer within a vented square cavity with dynamic flow modulation via a rotating heat conducting circular cylinder. External cold air is forcibly imposed through an inlet opening located at the bottom of the left wall of the cavity, while an exit port is placed at the top of the right wall. Isoflux heating is applied on the right wall, while the remaining solid wall boundaries are assumed insulated. A solid circular cylinder serving as dynamic flow modulator and rotating in counter-clockwise direction is placed near the bottom portion of the right heated wall. The governing mass, momentum, and energy equations representing the mathematical model of the present problem are solved in non-dimensional form using Galerkin finite element method. Parametric simulation is performed for wide range of governing parameters (Reynolds, Grashof, and Richardson numbers) within mixed convection regime under different dynamic conditions of the rotating cylinder characterized by the ratio of cylinder peripheral speed to mean inflow air velocity. Effects of the above governing parameters are analyzed through the visualization of streamline and isotherm plots, and the distribution of average and normalized Nusselt numbers of the heated wall, average fluid temperature in the cavity and the variation of pumping work required. Findings of the present study reveal that maximum heat transfer can be obtained by simultaneous increase of Reynolds and Grashof numbers, while careful selection of speed ratio of the rotating cylinder is necessary to obtain the optimum results within mixed convection regime. About 5.3% higher heat transfer enhancement is observed at highest speed ratio and higher Reynolds and Grashof numbers compared to the same for having stationary cylinder.