Modeling thermocapillary migration of interfacial droplets by a hybrid lattice Boltzmann finite difference scheme

To understand the motion behavior of interfacial droplets subjected to a temperature gradient, we built a simulation strategy integrated the phase field theory and the continuum surface force in a three-fluid system. In practice, a hybrid numerical scheme, coupling lattice Boltzmann (LB) for flows and finite-difference (FD) for fluids and heat transfer, was developed and then validated by droplet spreading and thermocapillary flows in a heated microchannel. We employed a two-dimensional finite deep model to study the thermocapillary motion of interfacial droplets. The results reveal the relation between the intensity of ambient thermocapillary flow and the direction of droplet motion, and demonstrate the effect of both droplets and interface deformations on droplet transfer. In particular, when the droplet largely deviates from the interface between ambient fluids, the deformation of the interface is obvious. These results are useful for the systematic investigation on the thermocapillary migration of interfacial droplets.