Numerical Simulation of a Contaminated Droplet by Front-Tracking Method Taking the Effect of Surfactant Transport on the Interface

In this study, a front-tracking (FT) method combined with a solver of interfacial transport of surfactant was proposed in order to resolve interfacial flows affected by contamination. In the FT method, because the interfaces are presented explicitly, advection-diffusion equation on the interface can be easily treated and can be solved highly accurately. In this study, a scheme which conserves the total amount of surfactant completely was constructed. Numerical simulations of a water drop sinking in silicone oil were performed taking the Marangoni effect into account. The effects of three parameters, a damping coefficient of interfacial tension, a diffusion coefficient and a total amount of surfactant, were evaluated. Calculated results were compared with PTV measurement results and were in very good agreement with them on the points of stagnant cap size, flow separation point, peak of shear stress and so on. So, we can expect that our simulations can estimate the conditions of surfactant on the interfaces, which is very difficult to be measured.