Dimensional Ns Equation Turbulence Model And Multigrid Applications

The present thesis deals with the solution of N-S equations. It includes three parts: the grid generation, the numerical scheme and the acceleration techniques. Hybird grids are adopted: structured grids near the wall and unstructured grids on the other field. A finite volume hybrid solver which is based on Janson'Finite-Volume scheme is developed, the S-A, k-ω and SST turbulence models are introduced. The agglomeration multigrid method is used. The agglomeration method is different in different fields in the turbulence flow simulation. Extensive numerical studies have been performed in order to access the accuracy of the present approach. All of results demonstrate the capability of simulating flow fields efficiently and robustly.The present work is mainly focused on the following aspects:1. The modified central difference method with artificial viscosity by Jameson is studied in spatial discrete about the convection terms of the N-S equations. The algorithm works in terms of cell faces, rather than the cells themselves, and the cells can be polygons of an arbitrary number of faces. An explicit four stages modified Runge-Kutta time stepping scheme is used. With local time step and implicit residual smooth method, the convergence procedure is accelerated.2. The one-equation Spalart-Allmaras model, two-equation k-ω model and SST model are applied to simulate turbulent. The capabilities of different turbulence models are compared through simulating the flow field over airfoils.3. The multigrid method is presented to speed up the convergence. The coarse grids are obtained by agglomerating the fine grids. The solution of coarse grid is driven by the fine grids'residue, and the solution on the coarse grids is used to correct the solution on the fine grids, which can eliminated all parts of frequency, the agglomeration method is different in different fields, especially for the solution of N-S equations.4. Extensive numerical studies have been performed in order to access the accuracy of the present work. All of works demonstrate the capability of simulating...