Numerical Simulation Of Hydraulic Characteristics In Confluence Between Yangtze River And Jialing River

Intersection at the waters of the Yangtze River and the Jialing River, the flow ofmutual backwater, water is complex and changeable, impact on shipping safety,sediment transport, river flood and pollutant migration. So, it is necessary toChaotianmen the mouth of two rivers meet to conduct a detailed study of hydrauliccharacteristics. Based on the systematic analysis of development history and researchstatus of flowing mathematic model, this text establishes Chaotianmen junction two andthree dimensional mathematic model using the SMS and Fluent computational fluiddynamics software, and studies the hydraulic characteristics of the confluenceemphatically. The main achievements of this paper are:(1) Calculated and analyzed the confluence of the rivers using the establishedtwo-dimensional model. The results show that: The gradient of the water surface atmain stream and tributaries of confluence upstream is subject to the convergenceratio; decrescence of the main stream of the water surface slope and the tributariesof the water surface slope increases are caused by the convergence ratio decreases.Water surface slope of the convergence mixing area is proportional to the mainstream flow and it is inversely proportional to the convergence ratio. In thedownstream section of the confluence, with the convergence ratio increase, waterlevel at the main stream side decreased, water level at the tributary side increasedgradually, the position of the two rivers converge gradually gets close to theChaotianmen spit and water demarcation line is near to the Jialing River side.(2) Analysis the three dimensional flow velocity distributions of cross-section then findthat: The shape of the separation zone is that the middle layer is big, while it issmall near the bottom and the surface of separation area. With the convergenceratio increases, the shape of the separation zone almost has no changes, but thescale of separation zone reduced accordingly; Entire flow cross section of channelis full of the anticlockwise secondary flow.(3) Analysis the spiral distribution of cross-section then find that the confluence is fullof positive helicity and negative helicity, and the center of negative helicity is closeto tributary side, while the center of positive helicity is near to the side of the mainstream; With the convergence ratio increases, the maximum positive decreasesoverall, and negative helicity first decreases, then increases a little， but thelocation do not change significantly. (4) For the same section, with the convergence ratio increases, the maximum values ofthe flow energy decreases overall. When convergence ratio is invariant, maximumenergy values of section shows a decreasing trend and minimum energy values ofsection are first decreases and then increase gradually.