Numerical Simulation Of Flow And Sediment Motion Near Submerged Dike

Submerged dike is one of the most important structures of port and coastal engineering, which has functions of adjusting water flow and diminishing siltation. Based on the open source computational fluid dynamics(CFD) program, discrete element method(DEM) program and open source coupling library, a three-dimensional numerical model for the gas-liquid two phase flow coupling particle motion is established to simulate the flow and sediment near the submerged dike. The main contents and conclusions are summarized as follows.(1) A three-dimensional model for the gas-liquid two phase flow simulation is developed on the basis of OpenFOAM, in which governing equations are three-dimensional RANS equations, the RNG k-? model is used to solve the turbulence, and VOF method is chosen to capture the free surface. A three-dimensional model for sediment motion is developed on the basis of a DEM code LIGGGHTS, in which governing equations are Newton's second law, and Hertz- Mindlin non-slip model is used to calculate the contact of particles. On the basis of the above two models, along with CFD-DEM coupling libraries under framework of OpenFOAM, the flow-sediment coupling model is established. Coupling related contents are added in the original governing equations of gas-liquid two phase flow model, so water-sediment particle interaction forces and data transfer are performed by the coupling library.(2) The flow characteristics of the open-channel are studied through the flow numerical model, and the velocity profile and the velocity distribution along the channel are analyzed. The flow model is verified by the comparison between numerical and experimental results.(3) Influences of time step on simulation results and the computing time consumption are analyzed through the particle motion model. The particle motion model is verified and reasonable range of time step in the model is confirmed.(4) The angle of repose of sediment particles under water are studied through the coupling model, and the effects of rolling friction force on the results are analyzed. The coupling numerical results agree with the experimental results.(5) The three-dimensional coupling model is applied to simulate flow and sediment motion near submerged dike. Due to the high computation cost of the coupling method, all the simulations are in the laboratory scale. The local flow fields of submerged dike under different flow conditions are simulated. On the basis of the flow field simulation, local sediment particle motion with and without submerged dike are analyzed.