Evaporating Rayleigh–Bénard convection: prediction of interface temperature and global heat transfer modulation

We propose an analytical model to estimate the interface temperature $\Theta_{\Gamma}$ and Nusselt number $Nu$ for evaporating two-layer Rayleigh-B\'enard configuration in statistically stationary conditions. The is based on three assumptions: (i) Oberbeck-Boussinesq approximation can be applied liquid phase, while gas thermophysical properties are generic functions of thermodynamic pressure, local temperature, vapour composition, (ii) Grossmann-Lohse theory thermal convection layers separately, (iii) content taken as mean value at gas-liquid interface. validate this setting using direct numerical simulations (DNS) a parameter space composed Rayleigh ($10^6\leq Ra\leq 10^8$) differential ($0.05\leq\varepsilon\leq 0.20$), which modulates variation state variables layer. To better disentangle variable property effects $\Theta_\Gamma$ $Nu$, performed two First, we consider case uniform except density diffusion coefficient. Second, include specific heat capacity, dynamic viscosity, conductivity realistic equations state. Irrespective employed setting, proposed agrees very well with over entire range $Ra-\varepsilon$ investigated.