A Predictive Model for the Migration of Double-Diffusive Interfaces

A model is proposed to predict the rate of entrainment and detrainment and the conditions for equilibrium for diffusive boundaries of a double-diffusive fluid layer. The system consists of a stably stratified layer overlying a mixed, turbulently convecting layer, which is representative of solar pond situations. The results show that the entrainment/detrainment laws are strongly dependent on the operating parameter range. At equilibrium, the density stability ratio at the edge of the convection zone depends only on the ratio of molecular diffusivities. The predictions are in satisfactory agreement with the available experimental data at large values of salinity and temperature gradients.