Author(s): Hans Bihs
Linked Author(s): Hans Bihs
Keywords: No Keywords
Abstract: Hydraulic structures in rivers present an obstacle for the water flow. This often results in rather complicated free surface patterns. In order to model the flow and other processes like for example local scour around hydraulic structures, the correct calculation of the free surface is essential. In the present study a three dimensional numerical model is used to predict the water elevation for flow around a rectangular pier. The model makes use of the level set method. With this frontcapturing method the free surface is modeled as the zero level set of a scalar signed distance function. When transported with the convection velocities, the level set function loses its signed distance property. In order to maintain this property and to ensure mass conservation, the level set function is reinitialized after each time step. Surface tension is taken into account with the the continuum surface force method. All convective terms including the level set and reinitialization equations are discretized with the fifth-order finite difference WENO scheme. It ensures a smooth and oscillation free solution for large gradients and even shocks while maintaining a high order discretization at the same time. The pressure is discretized with the projection method. The poisson equation for the pressure is solved with the preconditioned BICGSTAB algorithm. The staggered grid configuration leads to a tight velocity-pressure coupling. For time advancement a third order TVD Runge-Kutta Scheme is used. The model successfully captures the water level elevation around the obstacle.
Year: 2009