Numerical study of water wave generation by granular-liquid mixture collapse using two-phase material point method

Abstract

Debris flow sliding with high-speed and its possible interactions with a confined water body may lead to dangerous hazard. Therefore, it is important in practical applications to accurately predict the granular-liquid flows and their possible interactions with the water body. A two-phase material point method (MPM) with double-point formulation was applied in this paper to simulate the generation of the water wave by granular-liquid mixtures collapse into water. In our study, the debris flow was idealized as a granular-liquid mixture, the liquid phase was considered as a compressible viscous fluid, the granular response was modeled using the Mohr–Coulomb yield criterion and the granular-liquid interaction forces including viscous drag force and buoyancy force. Two experimental tests of dam-breaking flow and the wave generation by a dry granular column collapse were simulated, the accuracy and effectiveness of the proposed approach has been proven by comparing the numerical results with experimental data. We performed an experiment of saturated granular column collapsed into water and the test results were used to validate the proposed method, then applied the validated method to simulate the water wave generation by granular-liquid mixture collapse into water and investigate the effects of the initial degree of saturation defined as the initial depth ratio of water to granular material on the time evolution of the granular front and the amplitude of leading wave.