Research On Two-dimensional Water Release With SPH

With the development of computational fluid dynamics, examples of simulating fluid flow with computer, instead of physical model, are increasing. Traditional computational methods of flow simulation are numerical simulation methods based on grids. Computational grids may be the Lagrange-type or Euler-type. For some real situation, such as underwater explosion, water impact, and sudden water release problem, etc, the simulation methods based on grid may face great difficulties, due to the large deformation of grids. So a non-grid particle method, named SPH method, is used to simulate water movement as gate to be opened.The core idea of the SPH method is as follows. Firstly, a series of particles are distributed in the problem domain, without grid connects between particles. Secondly, field functions are approximated with integral. Thirdly, the approximate integral functions are discreted by using particle expressions. During the process, control equations of flow are changed from PDEs to ODEs. Finally, the ODEs can be solved with the explicit or implicit difference scheme. In the process of water release simulating with the SPH method, there are several key steps. First, in the integral approximation process smooth function is constructed, which influence directly on the accuracy of the simulation results. Second, in particle approximation process, the smoothing length needs to be selected seriously. Smooth length is related to the particle support domain. Too large support domain can not reflect the locality of the SPH method, and too small support domain in fluid not enough adjacent particles to affect the results of particles and resulting in the simulation error. Third, control equations are approximated with particle expressions and boundary conditions are dealt with. Fourth, technical proposal are designed, such as the time step selection, and the interaction between particles and NNPS, etc.The stage of development of SPH method is still in his infancy until now, so the research focusing on the SPH method is as follows:Firstly, the basic theory of the SPH method and related calculation systematically are summarized; Secondly,2D water release is simulated with the SPH method, and part of simulation data and some simulation graphics are provided; Thirdly, simulation results are analyzed, based on which the laws of the simulation data and the reasons of special phenomenon are provided in simulation graphics; Fourthly, the problem of the SPH method now and the research ideas of solving these problems are presented.