Experimental Study And Numerical Simulation Of Water And Sediment Movement In Mountain-bend River Confluences

Based on the existing research results and basic data analysis, carrying out flumeexperiment with theory analysis, this study analyzed the surface flow direction, surfacecontour distribution, relationship between separating zone and confluence ratio andinflow angle, water surface gradient change in the longitudinal and lateral direction atbending main stream confluence port of mountain river; studied the vertical velocitydistribution, longitudinal distribution, flow dynamic axis, velocity vector and shearstress distribution, circulation structure at confluence, turbulence kinetic energy andturbulence intensity; investigated the theory of erosion and deposition at confluence port,the bed-load moving regulation. By building the2-D modeling at confluence port, therelationship between confluence ratio and water surface gradient, confluence ratio andsurface flowing velocity, distribution of erosion and deposition and waterway depthchanging were analyzed; the affection by the upstream hydro-power station regulationto the water flowing and sediment transportation at river confluence port wasinvestigated further.This study results can not only be used to model the water flowing and sedimenterosion and deposition at upstream and downstream of confluence port by the mainstream and tributary stream, but also be used to summarize the water flowing andsediment transportation law, to provide the technical support on the study of waterflowing and sediment transportation law at confluence port. That has important valueson the development and management of the bending main stream confluence port in themountain river.The innovations in the dissertations are as follows:(1) This thesis first systematically studied flow characteristics and flow structuresaround the bend-mainstream confluence by the flume generalized model experiment.And combining with the actual river section, it preliminary revealed navigationmechanism of bend-mainstream confluence river from the theory.(2) It progressed formula fitting for relationships among the relative length and therelative width of the separation zone, discharge ratios, and inflow angles. And it gaveformulas for relationships among the relative length and the relative width of theseparation zone, discharge ratios, and inflow angles in the bend-mainstream confluencefor the first time. (3) The3D flow mathematical models was built. Models used orthogonalcurvilinear grid and unstructured triangle grid to split calculate area, this method solvedthe difficulty that occurred when3D flow simulation technology problem. It simulatedthe Three dimensional motion in confluences of the Yangtze river and toujiang river.Current character was shown at the junction of Yangtze River and Tuojiang Preliminary,which have a significance for channel maintenance and construction of this riversection.