Two-Fluid Numerical Model For The Simulation Of Reservoir Density Currents

Many of the rivers in our country contain much sand than other countries. The sediment silting, especially reservoir sedimentation is very important in river regulation field. During the comprehensive using and regulation of reservoir, sedimentation and erosion is the key point of reservoir life and efficiency. Using density current to eject sediment is one of the most effective methods for both prolonging reservoir working life and saving the limited water resource. There are many difficulties to observe density current in the field, so this paper builds numerical model to simulate the appearing and developing of density current. Compare the simulation result of reservoir density current velocity and concentration with the observation data and other experiment result, they match well. And this paper finds the impact of different setting of sand ejection gate.This paper builds two phase governing equations in Descartes coordinate separately, using two-fluid model. Then according to that the landform of reservoir is close to triangle, we adoptσcoordinate to be the computing region. Translate the formal control equations to the equations inσcoordinate. According to the finite volume method, disperse the new governing equations, and then translate the widely used Staggered-grid into the non-staggered-grids according with momentum interpolation method (MIM), for the non-staggered-grids can be more convenient for programming. Adopt SIMPLER algorithm, developing from SIMPLE algorithm to do the iterative solving.According to this paper simulation, author gets the Fr, at the reservoir density current appearing region, as the density current forming criterion, is between 0.72 and 1.16. This result well meeting many reservoirs observation and FanJia-ye's physical model data, Fr equals 0.78. Velocity and concentration profile data of reservoir density current also match FanJia-ye's and YaoPeng's data and other numerical simulations well.This paper sets six different vertical locations in reservoir dam for sand ejection gate, and then simulates these six projects to get the rate of sediment ejection. The rates meet reservoir observation data. Compare these rates and get the conclusion that the rate of the sand ejection becomes lower, as the vertical location of the sand gate becomes higher. This paper also simulate the appearing of the density current, when the input of water and sand fits the density current forming condition, to the disappearing, when the input of water or sand changes.