Modelling Droplet Evaporation with an Improved Coupled Level Set and Volume of Fluid (I-Clsvof) Framework

Abstract

Extended Abstract Modelling droplet evaporation is of great importance for many applications, such as inkjet printing, spray coating and combustion of fuel droplets [1, 2]. The key issues in the context of modelling droplet evaporation involve free-surface capturing [3], the phase change from liquid to vapour [4], and accurate calculations of the surface tension force [5]. Inaccurate calculations of surface tension force generate spurious currents or velocities which appear around the interface. Spurious currents destabilize the simulations and even influence the internal flow inside the droplets when studying droplets numerically [6]. In view of the issues mentioned above, we develop an improved Coupled Level Set and Volume of Fluid (i-CLSVoF) framework without explicit interface reconstruction for modelling micro-sized droplets with and without evaporation. A new surface tension force model with additional filtering steps is developed and implemented in the i-CLSVoF framework to suppress un-physical spurious velocities. Numerical benchmark cases demonstrate the excellence of the i-CLSVoF framework in reducing the un-physical spurious velocities (the un-physical spurious velocity converges to 10 −10 which is small enough to eliminate the influence of un-physical spurious velocities on the numerical stabilities). A simple yet efficient velocity-potential based approach is proposed to reconstruct a divergence-free velocity field for the advection of the free surface when the phase changes. The new approach fixes the numerical issues resulting from the evaporation-induced