Numerical Simulation And Visualization On 3-D Hydrodynamics

The target of this paper is to establish a software system which can be used to do things on 3-D hydrodynamic numerical simulation and data post-processing. Firstly, a 3-D hydrodynamic numerical modeling is established with non-hydrostatic pressure. For the discretization of the equation, the unstructed mesh system in horizontal direction and layer mesh in vertical which is converted toσcoordination during equation solving is used. To solve the equation, finite volume method and finite difference method are used together, and the software is programmed to achieve the numerical solution of model equations. Secondly, visualization to 3-D flow is achieved by programming, too. Thus, the software can be used to solve numerical solution and 3-D visualization simultaneously.Based on Reynolds equation and the k-εequation, turbulent closure model is setup. Considering the free surface, incompressible water etc., some constraint equations are taken in; this leads to the establishment of hydrodynamic model. Semi-implicit method and fractional step method for solving the model equations are adopted. First, the Reynolds equations under the assumption of hydrostatic pressure are solving and the intermediate velocity field. Then the correction term for the non-hydrodynamic pressure can be obtained by incompressibility condition. Finally, the new velocity fields are computed by correcting the intermediate velocity field with the gradient of hydrodynamic pressure correction term. Using finite volume method and finite difference method together, applying the kinematic boundary condition at the free surface, calculating convection and horizontal viscous term by the semi-implicit method, the use of these techniques makes it simple to solve these equations and ensures the stability of the discretization. Two test cases are used to prove that the model is perfect.Software is programmed to achieve stereometric simulation to 3-D flow with Microsoft WPF and anaglyph technology. The software can be used to achieve real-time dynamic visualization for 3-D surface flow, cross-section flow field and wave field, and it also can be used to simulate scalar fields such as pressure, temperature and concentration etc. To 3-D flow simulation, the paper proposes to use stereometric technology in 3-D simulation and achieves 3-D flow in Lagrangian. Anaglyph method makes it possible to show 3-D scene on 2-D screen and breaks through the limitations of how to show 3-D scene on 2-D display devices, and it leads to display 3-D scene with depth of field and hierarchical spatial relationship. It is an effective way to 3-D flow field simulation. During section flow field simulating, most efficient algorithms are composed to obtain vertical cross-section with arbitrary trends in horizontal and horizontal cross-section with most complex terrain. To place the cross-sections in the 3-D scene and display the cross-section flow by vertical projection makes cross-section flow displaying have a 3-D sense too. Surface flow simulation is not only able to float particles on water surface but also can simulate the dynamic water surface, so it makes a more vivid effect while dramatic changes in water level.3-D surface flow is different from 2-D flow with the background of 3-D terrain, and can demonstrate vertical 3-D surface flow characteristics. Lightweight WPF 3-D graphics platform, efficient data processing code and multithreaded programming techniques make the visualization system have extreme high efficiency, even in the ordinary dual-core computer; it can also have very good operating performance.