Exploring Thermal Dynamics of Periodic Bar Motion on Natural Convection in a Square Cavity

ABSTRACT Understanding the effects of fixed and moving bars allows for the design of more efficient thermal systems by using dynamic obstacles to optimize natural convection. This study complements several numerical studies on the effect of bars in a closed cavity. We examine the phenomenon of heat transfer by natural convection within a square cavity heated on the left side and cooled on the right side, with an adiabatic bar undergoing periodic vertical motion with an amplitude U bar and period T bar . We use the finite element method to solve the guiding dimensionless nonlinear equations. Our focus is on the effect of the bar movement direction, displacement amplitude U bar (0.1–0.4), displacement period T bar (1/3–1), bar width B (0.05–0.2), Rayleigh number Ra (10 4 –10 7 ), and number of bars N (1–3) on the average Nusselt number, streamlines, and isotherms distribution. The results show that increasing Ra significantly improves heat transfer. Maximum heat transfer occurs at U bar = 0.1 and T bar = 1. Increasing bar width and number negatively affects the average Nusselt number. This work contributes to understanding how dynamic obstacles can optimize natural convection, offering insights for the design of more efficient thermal systems.