Penetrative convection at low Pélet number

A theoretical one-dimensional model of penetrative convection in a stable temperature stratification heated from below has been developed in which the partial derivatives of temperature with respect to height and time are assumed to be discontinuous at the interface. As a finite temperature gradient then exists immediately above the interface, molecular diffusion effects at low Pélet number can be included. The results of the numerical-analysis model are used to illustrate the relative contributions of molecular diffusion, interfacial turbulence and the ‘filling’ of the existing temperature stratification by the lower boundary heat flux. Data from low-Pélet-number experiments are used to verify the results of the theoretical model.