Numerical simulation of water evaporation and evaporation-induced thermal convection in a bottom-heated cylindrical pool at low pressures

This paper examines water evaporation and the resulting thermal convection pattern in a bottom-heated cylindrical liquid pool under low-pressure conditions using three-dimensional numerical simulations. The effects of pressure ratio, heating temperature, and liquid depth on evaporation, temperature and flow fields, and Bénard–Marangoni (BM) convection structures are analyzed. The results show that the evaporation rate decreases as the pressure ratio increases. At fixed pressure ratio and heating temperature, the increasing liquid depth weakens evaporation by extending the heat-transfer path. At low heating temperatures, conduction dominates and BM convection cells do not form. With raising heating temperature, buoyancy and thermocapillary forces strengthen, producing diverse BM patterns. Lower pressure ratios intensify evaporative cooling, which can either suppress bottom-heated plumes by forming a cold cap or promote unsteady convection by enhancing vertical and interfacial temperature gradients. Thermocapillary circulation is more prominent in shallow layers, whereas the relative contribution of buoyancy increases with liquid-layer depth. These findings offer guidance for low-pressure evaporative cooling, liquid-pool thermal management, and interfacial phase-change heat-transfer control.