A multiphase smoothed particle hydrodynamics model with lower numerical diffusion

In this paper, a new multiphase SPH model with lower diffusion is developed for simulation of multiphase flows with large density ratios, complex interfaces, and strong impact. The zeroth-order density smoothing algorithm in previous models is replaced by a first-order density correction term which could effectively suppress density/pressure oscillation while lowering numerical diffusion. A switch-function-based artificial viscosity term is proposed to change the global implementation of numerical diffusion in the momentum equation into the local effectiveness depending on the strong impact. Such strategy aims to offer a good balance between the necessary numerical diffusion and the true physical viscosity of the fluid. In order to prove the robustness of the algorithm in various flow problems, five representative numerical examples, including Rayleigh-Taylor instability, internal solitary waves on the pycnocline, air bubble rising in water, oscillation of elliptic droplet and dam breaking, are presented. The expected advantages of the proposed method are demonstrated through comparison with the experimental data and previous numerical results. (C) 2019 Elsevier Inc. All rights reserved.