Evaporation Induced Thermal Patterns in Fluid Layers: A Numerical Study

Abstract

Liquid layers evaporating under the influence of a gas shear flow presents a non-uniform distribution of the evaporation rate all along the interface. Being the evaporation an endothermic process, a thermal gradient along the interface is generated and thermo-capillary flows are induced. Hence, two opposite mechanisms regulate the movement of the interface: the shear stress of the gas that entrains the interface in the direction of the flow and the thermo-capillary stress that forces the interface to move against the flow direction. The composition of these mechanisms at the interface generates an unstable thermal patterning. The dynamic evolution of the patterning and the relative evaporation rate are strongly influenced by the flow rate of inert gas, the layer thickness and the liquid thermo-physical properties. The goal of the present work is to study numerically how the evaporation process is influenced by the above-mentioned mechanisms. The focus will be on the evolution of the thermal patterning at the interface and the assessment of the main factors influencing the computed evaporation rate.