Numercal Simulation Of Flow Field And The Local Scour Pit Downstream Of Hengdan Hydropower Station

Scour damage downstream of hydraulic engineering has always been one of the mostimportant reasons to cause Hydraulic structures damage. Therefore correct prediction andforecast about the shape, depth and the internal flow field information of the scour pitdownstream of discharge buildings is of great significance for the discharge structuressecurity.The three-dimensional mathematical model of Hengdan Hydropower Station is set byFLUENT Software firstly with K-epsilon standard two-equation turbulence model being usedto close N-S equations, finite volume method being used to discrete grid, volume of fluid(VOF) being used to track location of water surface, and the flow field information issimulated and verified. Then through the C language and user-defined program, the secondarydevelopment of fluent software to simulate scouring process downstream of dischargestructures is completed, and finally the maximum depth and morphology of the scour pit isobtained. The result is as follows:(1) The corrected flow field information can be obtained by using the finite volumemethod (FVM) and the k-epsilon turbulence model;(2) The program made of C language and user-defined to complete secondarydevelopment of fluent software can effectively simulate the dynamic erosion process of thescour pit in two-dimensional;(3) The dynamic mesh method-local remeshing model included in FLUENT Software,can also calculate local scour process, and the calculated result is consistent with themeasured maximum depth and morphology of the scour pit;(4) Distribution law of local remeshing grid in the scouring process is as follows: gridnear the bottom boundary on moving is finer, and grid in the middle of scouring pit is coarser.It shows that there is a good quality of overall grid and the unstructured grid has strongadaptability;(5) Flow shear stress on the bed shows gradually decreasing in scouring process;(6) σ-adaptive moving grid technology can simulate two-dimensional scouring process atdownstream of discharge structures effectively; User-defined (UDF) program can control movement of bottom boundary of the scour pit effectively and adjust the internal gridposition，So there is a good and regular quality grid in the calculation process.