Simulation of aerolian sand transport with SPH-FVM coupled method

To overcome the drawback of discrete particle model (DPM) and Euler-Euler two-fluid model (TFM) in solving gas-solid two phase flow, a new method called SPH-FVM coupled method is presented, and then it is used to simulate aerolian sand transport problems. Based on a pseudo fluid model the smoothed particle hydrodynamics (SPH) is used to solve the discrete particle phase by tracing the movement of each individual particle, and the finite volume method (FVM) is used to discretize the continuum flow field on the stationary mesh by capturing fluid characteristics. Two phases are coupled through contributions due to the effects of drag, pressure gradient and volume fraction, and then the coupled framework of SPH-FVM is established. The properties of SPH are redesigned to be suited for the discrete phase named SDPH. The relationship between SPH particles and discrete particles is illustrated, and the SPH discrete equations of pseudo fluid are derived. Saltation processes of sands in aerolian sand transport, sand movement under free-air wind, and creeping processes of dune, are simulated; while the particle trajectories, the distribution characteristics of mean downwind velocity, and the changes of gas velocity under the sand reaction are analyzed. Through comparison with experiments, it is shown that the accuracy of the new method is high, and it can also reduce the computational cost. This indicates that the new method can be applied to aerolian sand transport even to other gas-solid multiphase flows.