Author(s): Lingling Wang
Linked Author(s): Lingling Wang
Keywords: Large eddy simulation; Momentum jet; Multi-grid method
Abstract: A momentum jet in environmental water is typical phenomena in coastal engineering in which the waster water is discharged into the ambient water through an outfall system. It is important to study and quantify the mixing of the discharge so that an accurate environmental impact assessment can be made for such discharge condition. In this paper, phenomenon of a plane jet both in stagnant environmental water and in regular wave is studied by using multi-grid method inσ-coordinate system. Theσ-coordinate transformation is introduced to map the irregular physical domain with the wavy free surface and uneven bottom to the regular computational domain with the shape of rectangular prism. Numerical model based on the full Navier-Stokes equations (NSE) is developed under the concept of large eddy simulation (LES). The operator splitting method is employed to solve the modified NSE. Multi-grid method with four-color Gauss-Seidel relaxation combining with 7-point finite difference scheme is adopted to solve the propagation step. Numerical predictions include mean velocities, the decay rate of the centerline velocity etc. Numerical results are compared to available simulation values. Good agreements are obtained. The model is verified high efficiency with satisfied convergence speed. It turns out that the multi-grid method is very useful tool in simulation complicated turbulence.
Year: 2004