Modeling and simulation of mixed convection flow with viscous dissipation in a lid-driven hexagonal cavity using finite element method

The computational analysis of mixed convection flow with viscous dissipative heat transfer inside a hexagonal enclosure cavity is done in this study using the finite element method. The upper side of the cavity is kept cold and moves from left to right at a constant velocity, while the lower side of the cavity is thermally motivated by a fluctuating sinusoidal temperature. The non-parallel sides of the hexagon are maintained with adiabatic. The governing equations of flow are converted into a dimensionless form and then computed with the help of Comsol-Multiphysics software. The cavity's internal transport processes are examined across a wide parametric range such as the Reynolds number (10≤Re≤1000), Eckert number (0≤Ec≤50), and Richardson number (0.1≤Ri≤10). It was found that the flow in the cavity is governed by the motion of the upper lid and the buoyancy force produced by the temperature differential in the cavity. The effects of Reynolds number, Richardson number, and Eckert number on flow velocity, thermal distributions, and local heat transfer rate are examined. The findings show that the intensity of the temperature value improved from 1.85 to 12.22 as the Eckert number increased from Ec=0 to 50. Physically, the greater value of Ec generates more heat as a result of work done against the viscous fluid stress, and it improves the thermal distribution in the cavity. The outputs also reveal that the heated wall reports the highest values of the local and average Nusselt numbers when the Eckert number is zero, and they tend to decrease as the Eckert number increases. The cold-moving wall, on the other hand, reports the opposite effect. Furthermore, convection dominates the local heat transfer at the cold moving wall, whereas, at the heated wall of the cavity, conduction plays a more significant role in local heat transfer. © 2024 The Author(s)