Based On The Sph Method Of Numerical Simulation And Visualization Of Free Surface Flow

The flowing problem of the fluid that has free surface has a great deal of existence in the engineering, such as ocean engineering, petroleum chemical engineering,, hydraulic engineering and mechanical engineering . etc. For example Wave propagate, transform, break and interact with structures in ocean engineering; During the wind blow the lake surface, the pollutant diffuse in lake; And the problem of crest overflow and the flow under the gate in hydraulic engineering, etc. The famous water conservancy studying organization of some developed countries have already from past with physical model experiment is main research means, gradual conversion for simulation to lay equal stress on with physical model by numerical or with numerical simulation is main research means. Such as the Delft hydraulics laboratory of Holland and the Advanced Scientific Computing Ltd of Canada, etc. all obtain a better result in aspect of the numerical simulation and visualization of its result. The free surface flow because of its existence variational boundary, the boundary position is knew in the initialization, henceforth the boundary position need to be a part that computing result to carry on solving, so the free surface flow of numerical simulation always is a great hard and nuts problem in the computing hydrodynamics. This paper uses a kind of new method-mesh free method-SPH method, process the flowing problem of the fluid that has free surface, and apply to the numerical simulation of dam bursting and crest overflow of overflow dam in hydraulic engineering.The SPH method as one of mesh free method, opposite to the method based on the mesh that has the problem of carrying out mesh demarcation and taking place mesh mutation, mesh ambulation during the period of solving , have more obvious advantage. The kernel theory of the SPH method is to use a series of particles to disperse the continual system, these particles take an independent physical information and flow under the physical controlling equation. A two-dimensional hydrodynamic model is developed, on the basis of studying thoroughly on the principle of Smoothed Particle Hydrodynamics (SPH) method and applying the numerical approximation formulations of SPH to N-S equation. The pressure adopt the equation of state to compute ,because of introducing in the artificial compression rate. The boundary processing adoption that doesn't exert any condition to the free surface ,and a new method of a standard explicit project-and-reflect is used to deal with the fixed boundary condition. Using to lay several layers of virtual particles to satisfy the density of boundary, and judging whether the inside particles have penetrated into the boundary and go on dealing with explicit project-and-reflect. For because of shortage of particles in the supporting area bringing the influence adopt the variable smooth length method to resolve. In the meantime introducing in "particles system" to handle flow interrupted problem. Through out the above research going on simulating dam breaking, and crest overflowed of overflow dam, the result accord with the real condition. The result shows that the SPH method have a good function to solve the two problem, and the boundary processing method that mentioned can ensure the stability of the boundary pressure. Finally adoption "particles system" to get more intuitionistic expression.