Dynamics of the steam-air mixture in the gap between a drop and a solid substrate

Abstract

This paper presents the results of numerical modeling of the air and water vapor motion from beneath a drop hovering over a hot solid substrate. A similar problem was previously solved in a simplified formulation using a modified equation for water vapor concentration with model-based consideration of convective transport. In the present study, the full system of Navier – Stokes equations is used to describe mass transfer of the steam-air mixture. The physical model is closed using the equation of state for a two-component ideal gas. The problem is solved numerically with the help of the finite difference method in an axisymmetric formulation. The obtained velocity fields for the steam-air mixture and for the vapor concentration demonstrate the presence of excess pressure beneath the drop due to intense evaporation caused by heating from the hot substrate. For experimental values of the material parameters, the possibility of a drop levitation above the substrate is demonstrated. The presented data are in good agreement with the calculation results previously obtained using a simpler approach.