A coupled CFD-DEM method with moving mesh for simulating undrained triaxial tests on granular soils

A coupled computational fluid dynamics and distinct element method (CFD-DEM) is proposed to simulate undrained triaxial tests on granular soils. In this method, the compressible volume-averaged Navier-Stokes equations of continuity and momentum with an additional state equation are used for modelling liquid flows. In addition, the volume-averaged Navier-Stokes equations are modified by including the velocity of moving grid in their convective terms to settle the problem of variable boundaries in the process of undrained triaxial compression. Then the capability of the developed method is mainly examined by comparisons with the constant volume method of simulating undrained triaxial tests, which shows that the results of the CFD-DEM method can compare favourably with those obtained from the constant volume method. Finally, the influences of strain rate, initial pore pressure and fluid compressibility on the undrained behavior of granular soils are carefully studied.