| Spur dike as buildings of waterway regulation,in the actual engineering of mountainous rivers are widely used.The construction of spur dike can narrow the beam flow and increase the depth of the channel.At the same time,it also can reduce the flow velocity of inshore and protect the river bank.While it also can cause flow separation and return at the same time,the flow near in the spur dike present complex three-dimensional characteristics.Using the three dimensional flow model of spur dike to simulate the flow field changes has practical reference value for the planning and design of waterway regulation engineering.So far,about double spur dike near area,the three dimensional numerical simulation of flow field about double spur dike is less.And the flow field calculation about spur dike are mostly limited to the section average flow velocity.So the research of the three-dimensional flow characteristics about double spur dike has important theoretical and engineering significance.This paper is based on the computational fluid dynamics theory and discrete the three dimensional area in tetrahedral unstructured grid.With the help of fluent software,it units flow continuity equation,momentum equation and the two equations of standard k-epsilon and solve to get the results.The finite volume method is adopted to discrete the equation and use the PISO algorithm to solve the discrete equations.At last,it simulate the three-dimensional flow characteristics around the double spur dike accurately and made the following several aspects of research.(1)The simulation results show that using the VOF party to capture the free water surface line around spur dike and tallies well with the actual situation,the simulation effect is better.Using the three-dimensional turbulent flow model and two equation model of k-? to calculate the turbulence kinetic energy and turbulence dissipation rate around the double spur dike has more reliable results,the research methods can provide certain theoretical support to the corresponding physical model experiment and theoretical analysis.(2)The free surface lines captured by the VOF method are analyzed and get the lateral distribution about the free water surface line in front of the dam,in the middle of spur dike and in the back of the spur dike.It also obtains the longitudinal distribution offree water surface lines in the mainstream zone,attachment region of jetty head and near the left bank.(3)By using Tecplot post-processing software to analyze the results of three dimensional numerical simulation,we get the lateral velocity distribution of cloud in front of spur dike,in middle of spur dike and in back of spur dike when the length,water depth and forms of the spur dike head are different.It also obtains the velocity distribution along the longitudinal in the mainstream area,attachment region of jetty head and of the region close to the left bank,as well as the distribution of velocity in the vertical direction.(4)Through the post-processing function of fluent software,I obtain the distribution of cloud and scatter distribution of turbulence kinetic energy and turbulence dissipation rate in the bottom,middle layer and the top layer of water.They contain the distribution along the lateral,longitudinal and vertical direction.Through the analysis of these distribution results,the regularities of distribution about the turbulent kinetic energy and turbulence dissipation rate when the length,water depth and the distance is different is obtained.They include the regularities of distribution along the longitudinal,horizontal and vertical direction,as well as the location of the maximum turbulent kinetic energy and turbulence dissipation rate.(5)By displaying the distributions of dynamic water pressure in the form of three-dimensional stereogram analyze the results of different conditions,we obtain distribution nephogram of dynamic water pressure in the condition of different spur dike lengths,water depths and angle of spur dike.We also obtain the location of the maximum dynamic water pressure. |
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