Numerical Simulation Of Flow Field And Scour Near Grooved Dams

Natural rivers interact with water and sand to trigger riverbed evolution.In order to eliminate the disease,appropriate measures must be taken to remediate the river,including diversion,dredging and revetment works.As a common hydraulic structure,Ding Dam plays a role in guiding the mainstream and protecting the shore beach in river improvement projects.The relationship between dam length and river width should be considered in the river treatment planning of Ding Dam,and the longer the Ding Dam,the greater the flow velocity at the head of the dam,which will cause the riverbed on the opposite bank to be washed out.If it is too short,the length of cover on the shore of the Ding Dam will be reduced.In addition,the water conditions in natural rivers are complex,and studying the flow pattern of water flow has engineering guiding significance for the setting of Ding Dam.In this paper,the river width and narrowing rate is taken as an engineering factor,different water conditions are taken as natural factors,different Floword numbers are selected to characterize different water flow conditions,and three median particle sizes of sandy riverbed are taken for numerical simulation study.In this paper,the river width and narrowing rate,Froud number,single ding dam,ding dam group and other elements are taken as the research objects,and the longitudinal section of the river channel,the cross-section of the dam axis,the flow rate and water level of the dam body are analyzed and studied,and the erosion process and simulation of the terminal riverbed state and the erosion rate of the dam head are analyzed in detail.After simulation analysis,the conclusions are as follows:(1)The setting of the Ding Dam accelerates the local deepening of the riverbed,but it has a role in preventing erosion on the shore beach on the side of the Ding Dam.The greater the river width and narrowing rate,the greater the degree of water drop at the dam head,the greater the relative return length behind the dam,the greater the extension of the high flow velocity area at the dam head,the greater the local erosion depth of the dam head,and the more serious the erosion on the opposite bank.(2)The Flowuder number is the node of the flow field change at 0.4,and the flow field in the upper and lower mainstream areas of this node and the internal flow field of the dam field have changed to varying degrees,and the water level,flow velocity and scale of the vortex return zone after the dam on the longitudinal section and the cross-section of the dam axis have changed accordingly.(3)Under the same median particle size,the larger the Fraude number,the greater the erosion depth of the riverbed,while under the same Froster number,the larger the median particle size of sediment,the smaller the local erosion depth near the Ding Dam.In the stage of sandy riverbed erosion equilibrium,the sand transport rate is not zero;The distribution of the maximum sand transport rate is not related to particle size,only to the Froud number,and the size of the maximum sand transport rate is related to particle size.