Accurate prediction of generalized oil-water interface evolution with a novel multiphase SPH scheme

In multiphase SPH method, accurate prediction of oil-water interface is a key, and a major source of failure is due to the nonphysical pressure oscillation. Then in this work, a novel multiphase SPH scheme is designed to solve this problem by integrating several treatments of pressure oscillation together, when the generalized oil-water two-phase flows are simulated. These treatments are: (1) the revised diffusive term which is added in the continuity equation by replacing the original density with the density increment; (2) the corrected density re-initialization during whose implementation different-phase fluid particles must be converted into the imaginary same-phase ones; (3) the particle shifting technique to distribute particles more uniformly. Through the simulation of several generalized oil-water two-phase flow problems as well as comparison with reference solutions, it is validated that our novel SPH scheme is stable, accurate and with less dissipation, and can avoid particle penetration near interface. Finally, a new and more complex generalized oil-water two-phase flow problem is designed and simulated to further demonstrate the above advantages of our SPH scheme.