Suppressing flow reversal and modulating heat transfer in turbulent square convection via a half-length isothermal hot plate

This paper investigates turbulent Rayleigh–Bénard convection (RBC) within a two-dimensional square cavity, heated only by a partially isothermal hot plate on the bottom wall. Unlike RBC with two partially isothermal hot and cold plates at the bottom and top walls, respectively [Hu et al., J. Fluid Mech. 987, A9 (2024)], where large-scale circulation (LSC) reversals depend on the relative positioning of the two plates, the single half-length bottom heater eliminates the corner-roll feeding mechanism, resulting in a position-insensitive suppression of well-defined flow reversals with Ra=108,Pr=2. This suppression is explained by two factors: the localized heating provides insufficient energy input to sustain and strengthen corner rolls beyond the reversal threshold, and the flow stability is significantly enhanced compared to standard RBC. A notable finding is that as the plate moves toward the center—restoring left–right symmetry—the flow stability, kinetic energy, and heat transfer efficiency increase simultaneously. These findings offer a simplified and physically transparent approach for controlling flow reversals and modulating heat transfer efficiency by modifying non-uniform conducting boundaries.