Evaporating droplets: comparisons between DNS and modelling

This study focuses on preliminary analysis of the heating and evaporation processes in a spherical moving droplet using Direct Numerical Simulation (DNS) and simplified modelling approaches. DNS of two-phase flows is used to obtain detailed information about heat and mass transfer at the interface. The DNS results are compared with the results predicted by the modelling approach, based on the analytical solution to the heat transfer equation inside the droplet. The latter approach takes into account the finite thermal conductivity and recirculation inside droplets using the effective thermal conductivity (ETC) model. The ETC model has been widely used by the scientific community since it was originally developed by Abramzon and Sirignano more than 25 years ago, although its range of applicability has never been rigorously investigated. The comparison between DNS and modelling results is performed for a wide range of Peclet numbers in the analysis of transient heating of droplets without evaporation. A DNS database has been created. DNS results are shown to be rather different from the modelling results when the model is used for relatively low Peclet numbers. These results, however, turned out to be in good agreement for relatively high Peclet numbers