Transition between Boundary-Limited Scaling and Mixing-Length Scaling of Turbulent Transport in Internally Heated Convection

Abstract

Heat transport in turbulent thermal convection increases with the thermal forcing, but in almost all studies the rate of this increase is slower than it would be if transport became independent of the molecular diffusivities -- the heat transport scaling is slower than the mixing-length (or `ultimate') scaling. In configurations driven by either thermal boundary conditions or internal heating, thermal boundary layers instead lead to a boundary-limited (or `classical') scaling. With net-zero internal heating and cooling in different regions, mixing-length scaling can occur because heat need not cross a boundary. We report numerical simulations in which heating and cooling are unequal, as in various natural systems, at a Prandtl number of unity. As heating and cooling rates are made closer, the scaling exponent of heat transport varies from its boundary-limited value to its mixing-length value.

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Cited by in corpus (6)

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• Internal heating profiles for which downward conduction is impossible
• Rigorous scaling laws for internally heated convection at infinite Prandtl number
• Internally heated and fully compressible convection: flow morphology and scaling laws
• Ultimate regimes in horizontal and internally heated convection
• Prandtl number dependence of rotating internally heated convection