Improved phase-field-based lattice Boltzmann model for liquid-gas flow with evaporation.

Abstract

In this work, an improved Allen-Cahn-based phase-field lattice Boltzmann model is presented which is applicable to heat transfer in two-phase flow involving evaporation. The vapor concentration at the liquid-vapor interface serves as the driving force for vaporization. In our improved model, four distribution functions are used to describe the velocity field, the phase field, the temperature field, and the vapor concentration field where the vapor concentration and temperature fields are coupled by the Clausius-Clapeyron correlation. We evaluate several numerical tests to verify the accuracy of the presented model, including the one-dimensional (1D) Stefan flow and the two-dimensional or three-dimensional (2D or 3D) droplet evaporation problem. The results obtained demonstrate good agreement with theoretical expectations. We also compare two evaporation driving modes: the temperature gradient and vapor concentration gradient. Additionally, we investigate the impacts of the volume expansion rate term F_{β} and the volume-specific heat gradient term T_{α} on the model. In the case of 1D Stefan flow, the result without T_{α} exhibits the largest deviation of 52.1% at Y_{v,I}=0.8, while the result without F_{β} shows a deviation of only 12.2%.