Dynamics of an evaporating drop migrating in a Poiseuille flow

TL;DR

This study models the evaporation and deformation of a liquid drop in a Poiseuille flow using a coupled CLSVOF method, revealing steady heat and mass transfer coefficients and the influence of flow parameters.

Contribution

It introduces a robust phase change model with an embedded boundary method for vaporizing flows and validates it against benchmark problems.

Findings

Sherwood and Nusselt numbers reach steady values after initial transients.

Drop deformation has minimal impact on evaporation rate.

Sherwood number correlates linearly with Re^{1/2}Sc^{1/3}.

Abstract

The evaporation of a liquid drop of initial diameter (Ddrop) migrating in a tube of diameter (D0) is investigated using the coupled level set and volume of fluid (CLSVOF) method focusing on determining the heat and mass transfer coefficients for a deforming drop. A robust phase change model is developed using an embedded boundary method under a finite difference framework to handle vaporizing flows. The model is extensively validated through simulations of benchmark problems such as arbitrary evaporation of a static drop and reproduction of psychrometric data. The results show that the Sherwood number (Sh) and the Nusselt number (Nu) reach a steady value after an initial transient period for the drop subjected to Hagen-Poiseuille flow. A parametric study is conducted to investigate the effect of drop deformation on the rate of evaporation. It is observed that Stefan flow due to evaporation has a negligible impact on the drop deformation dynamics. We also observed that, for different values of Ddrop/D0, the Sh follows a linear correlation with Re^{1/2}Sc^{1/3}.