Two-Dimensional Numerical Simulation Of Flows Based On Unstructured Mesh

Numerical simulation is used to study hydrodynamic problems becomes the importantresearch stage, and as laws of nature reveals day by day that numerical describes reflect thenature increasingly and the affect and influence are more important. The two importanttechnology of flow’s movement numerical simulation contains the generation of computablemesh and the numerical discrete technology. Mesh is the premise and base of numericalsimulation, the quality of mesh can have a marked impact on both simulation precision andcomputing efficiency. In this paper,aiming at the difficulty that the complex computable areafacing the irregular boundary fitting and local compact simulation, based the delaunay andadvancing front method, studied a triangle unstructured mesh auto generation technology thatjoined these two methods together and used to divide any computable area with triangle mesh,solving problems as the complex boundary fitting and local mesh encryption.High-precision scheme like(FDS,FVS,OSHER) to calculate local Riemann problem toestimate each mesh interface’s normal numerical flux, making the flow model with goodconservation、upwind and handling interruption problem and complicated boundary.Based on the FVM to solve the Riemann problem, by the Gausss Theorem,the surfaceintegral in the element unit is changed to the line integral in the element boundary, because ofthe Eulerian equation’s rotation invariant, the2D shallow water equations is simplified to1D equations, greatly simplifies the solution of the model. The equation is divided to the timeterm, convective term, diffusion terms and source term (including the bottom slope term andthe friction term)，the key of the model is to solve the Riemann approximate solution to getthe convective term.In this paper, the computational area is divided with unstructured grid, the feasibility isproved by simulating the1D flat bottom dam break problem and comparing with the precisevalue; the feasibility of simulating the strong discontinuous flow is proved by simulating the2D flat bottom and uneven dam break problems and has the ability to deal with the movingboundary.In the project example of both ocean model Caofeidian and river model Daijiazhouare usd to verify the water level, velocity and direction, the calculated datas are matched withthe measured value, and further do the program project.