Numerical Simulation of Thermocapillary Migration of a Droplet on Temperature Gradient Wall

Numerical simulation of droplet migration phenomena on a temperature gradient wall was performed to realize efficient droplet behavior control by applying a temperature gradient in a microfluidic device. In order to accurately simulate such phenomena numerically, a numerical method that can capture the behavior of droplets with high accuracy without artificial treatment near the gas-liquid interface is required. To satisfy these requirements, the Conservative Phase Field method was employed to capture the gas-liquid interface. In order to capture the interfacial behavior with high accuracy, the level-set method was coupled to calculate the interfacial curvature and surface tension using a signed distance function. To simulate wettability on solid walls, wettability boundary conditions were applied to the distance function. Validation results show that the numerical method used in this study can accurately estimate the effect of surface tension on the flow field for non-isothermal gas-liquid two-phase flow problems with a small number of spatial grids and can accurately represent wettability over a very wide range of set contact angles. Finally, in the analysis of droplet migration phenomena on a temperature gradient wall conducted using this method, the results of the present study showed good agreement with the theoretical solution, confirming the improvement in accuracy from the results of previous studies.