An Improved Single-Layer Smoothed Particle Hydrodynamics Model for Water–Soil Two-Phase Flow

Abstract

In coastal and offshore engineering, the intense water–soil motion poses significant challenges to the safety of buildings and structures. The smoothed particle hydrodynamics (SPH) method, as a mesh-free Lagrangian solver, has considerable advantages in the numerical resolution of such problems. SPH models for the water–soil two-phase flow can be categorized into the multilayer type and the single-layer type. Although the single-layer model envisions a simpler algorithm and higher computational efficiency, its accuracy, stability, and recovery of interfacial details are far from satisfactory. In the present work, an improved single-layer model is established to alleviate these limitations. First, the soakage function, which takes effect near the phase interface, is introduced to characterize the two-phase coupling status. Additionally, the stress diffusion term and a modified density diffusion term applicable in density discontinuity scenario are introduced to ease the numerical oscillation. Finally, to remove the unphysical voids in the interfacial region, the particle shifting technique with special treatment tailored for free-surface particles is implemented. Validations of the proposed model are carried out by a number of numerical tests, including the erodible dam-break problem, the wall-jet scouring, the flushing case, and the water jet excavation. Appealing agreements with either experimental data or published numerical results have been achieved, which verifies the accuracy, stability, and robustness of the proposed model for water–soil two-phase flows.