A One-Dimensional Vertical FEM Model Of Water-sediment Interaction

Having summarized the theory and method in the previous study of the trubulence flow and sediment diffusion, a suitable model for calculating the velocity and concentration distribution of sediment-laden flow that involves the water-sediment interaction is proposed, based on the opinion of considering the the hyperconcentrated flow as Bingham fluid in the near bottom zone.The governing equation can be discreted into the linear equations by Galerkin finite element method after using the partial integration and Green's Theorem and then the Gauss elimination solution of equations is applied.In mathematical model, the original terrain data often appears as a serious of planar point coordinates, which are gathered to provide the boundry of simulation region manually. In order to reduce the workload, an algorithm of searching for the proper boundry is presented on the basis of given point set. The algorithm proves good results in the boundry search for boundry points of Bahia area. In the last part of this paper, the proposed mathematic model of water-sediment interaction is applied to the numerical simulation and verification of previous experiment data. The calculating results match well with the measured value, which confirms its feasibility on simulation of pratical working condition. Some examples are tested with the model and the distributions of velocity and concentration are analyzed afterwards. According to the simulation results, a new viewpoint is put forward that there exists a course from large to small for the velocity gradient in the near bottom zone because of the Bingham shear stress.The one-dimensional vertical FEM model of water-sediment interaction proposed in this paper shows new thoughts and approaches for the study of the sediment-laden flow.