An Allen–Cahn-based lattice Boltzmann model for two-phase flows with surfactants

Accurately modeling two-phase flows involving the surfactant is of great significance for understanding the interface evolution dynamics due to the variation of surface tension. In this study, we proposed an Allen–Cahn-based lattice Boltzmann model for two-phase flows with soluble surfactants, in which a new force scheme from the view of continuous surface tension force scheme and the consistent wetting boundary condition are derived. Several numerical tests are conducted, and the results are compared with the model based on the previous potential form (PF) interfacial force scheme. The results indicate that our proposed model can model two-phase flows involving the soluble surfactants, even for high-density ratio situations. The distribution across the interface is accurately predicted. Our model also shows superior performance on two-phase dynamics involving surfactants, i.e. smaller spurious currents and larger range of contact angle. This model can be a favorable alternative for high-density-ratio two-phase flows involving soluble surfactants.