Thermal convection driven by a heat-releasing scalar component

In this paper, we investigate the thermal convection flow which is driven by a heat-releasing concentration field. Different from our previous work on the internally heated double diffusive convection (IHDDC), in the current internally heated Rayleigh-Bénard convection (IHRBC), the fluid density depends solely on the temperature field and the concentration field only serves as the internal heat source. Linear stability analyses reveal that the most unstable mode is always the stationary one. The critical Rayleigh number, which measures the strength of the unstable driving force, decreases with the Schmidt number (the ratio between the viscosity and the molecular diffusivity of concentration field), but increases with the Prandtl number (the ratio between the viscosity and the thermal molecular diffusivity). Fully developed flows are then studied by three-dimensional direct numerical simulations. The unifying model developed for IHDDC can also be used to describe the transport properties for the current flow. The characteristic widths are smaller for the plumes descending from the top plate than those ascending from the bottom one.[Figure not available: see fulltext.]. © 2022, The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature.