Thermocapillary Flows in Self-Rewetting Drop Impingement over Nonuniformly Heated Fluid Layers and in Enclosed Containers: A Lattice Boltzmann Study

Self-rewetting fluids (SRFs) (e.g., long-chain alcohol solutions) are a special class of liquids with surface tension anomalously dependent quadratically on temperature. They exhibit significantly different thermocapillary flows compared to normal fluids (NFs) and have recently found various applications. We will present two case studies to illustrate the differences in the interfacial transport phenomena occurring in SRFs when compared to NFs. In this regard, we utilize a central moment-based lattice Boltzmann method (LBM) with three distribution functions: one to compute the two-fluid motion at high density ratios with attendant Marangoni stresses, another one for interface capturing via solving the conservative Allen-Cahn equation, and finally, the third one to compute the energy equation. In the first case study, we will perform axisymmetric simulations of a drop impinging on a SRF liquid layer subject to nonuniform heat fluxes represented as a Gaussian profile. We will study the coalescence and pinch-off processes and their dependence on the various characteristic parameters. In the second case study, we investigate thermocapillary convection in SRF layers enclosed inside a square cavity which is subject to a localized heat flux on one of its sides.