Numerical Simulation of Long-Distance Diversion Tunnel with Free Flow Based on the VOF Method

Abstract

The 3D standard k -ε model of water-air twophase flow coupled with Volume of Fluid (VOF) method is established in long-distance diversion tunnel with free flow. Considering the wall roughness, the method of Wall functions is adopted near the walls. The results show that the disturbance zone of water flow appears at the inlet. The mutation zone of water flow and air flow vortex appear at the outlet. Water flow vortex appears at the intersection of main tunnel and branch tunnel. The calculated results are compared with the water depth data measured in the drainage and emptying tunnel of a reservoir, indicating that the simulation results agree well with experimental ones. Keywords-long-distance diversion tunnel with free flow;water-air two-phase flow; VOF method; 3D standard k -ε model; Computational Fluid Dynamics (CFD)

Numerical Simulation of Cavitation and Aeration in Discharge Gated Tunnel of a Dam Based on the VOF Method

“…Two phase cavity flow is modeled by using VOF method here. In this method it is assumed that both phases have the same velocity in a cell and a series of equations can be used for the flow field like a single-phase flow [7]. In this method a function (f) is used to determine volume fraction of liquid in a cell and can have three quantities; f=0, 0<f<1, f=1 which respectively shows that the cell is full of air, includes both air and water and is full of water.…”