Improved approximation of the interfacial tension for the flow simulation of suspensions of bubbles and droplets

This work considers the description and simulation of two-phase flows. For the description of two immiscible fluids, the volume of fluid method is used. In the first part, an improved computational scheme for the curvature field is developed. It is based on the signed distance field. The scheme is implemented within Open FOAM and is coupled with an already existing two-phase solver. The results show a significant reduction of the numerical error. The scheme is validated for free-surface flows and moving contact lines. Moreover, experiments of the bubble-point test are performed and used as a reference to validate the computations. The results show that the simulations can reproduce the experiments better than before. In the second part, the developed method is applied to a liquid-liquid separation process. The separation of water droplets from diesel is investigated. For this case, the interaction of a single water droplet with a hydrophobic wire-mesh screen is studied. Through a series of simulations, insights on droplet deformation, retention or drainage velocities could be obtained. The models correspond approximately to the numerical simulations with deviation less than 10%.