Numerical Simulation of Water-Filling Process in Long-Distance Diversion Tunnel with Free Flow

The 3D standard k - ¿ model coupled with the volume of fluid (VOF) method of water-air two-phase flow is established in long-distance diversion tunnel with free flow. The method of wall functions which considers the roughness of the walls is utilized near the walls, and the method of pressure-implicit with splitting of operators (PISO) is applied to solve the unsteady water-air two-phase flow field. The results show that water level in the tunnel increase with filling time and tend to arrive at a steady state. The dynamic analysis results of water-air two-phase flow of typical section in water-filling process show that when the inlet flow rate is 74 m³/s, the flow can pass through the tunnel smoothly. The different water levels in the drainage and emptying tunnel of a reservoir are calculated. The calculation results agree well with the experimental ones.