The impact of a single wave generated by a dam break with a tall structure is modeled with a three-dimensional version of the Moving particle semi-implicit (MPS) method. The particle method is more feasible and effective than methods based on grid connection problems involving the violent free surface motions. In the present study, the incident bore impact load and the change of longitudinal velocity component around the structure, which are obtained from the numerical simulation, are compared those from experiments by Arnason (2005).
The accurate prediction of impact loads by fluid gives important information for safety of ships or maritime structures. The large deformation and dynamic behavior of free surface are one of the most difficult problems for numerical simulations because the numerical implementation of the fully nonlinear free-surface condition is in general complicated and difficult. There are several techniques to handle such kinds of problems, i.e. SOLA-VOF (Hirt and Nichols, 1981), Level-Set (Sussman et al., 1994), Marker-Density function (MDF) (Miyata and Park, 1995) etc.. Most of them are the techniques capturing the free-surface on grid system. However, there is a different approach using no-grid system, so-called particle methods by use of moving particles with the Lagrangian treatment. The particle methods seem to be more feasible and effective than conventional grid methods for solving the flow field with complicated boundary shapes or the coupling effects between fluid and structure. In the present study, the violent free-surface motions interacting with structures are investigated using the Moving Particle Semi-implicit (MPS) method, which was proposed by Koshizuka and Oka (1996) for incompressible flow. In the method, Lagrangian moving particles are used for solving flow field instead of Eulerian approach using grid system. The method consists of the particle interaction models representing gradient, diffusion, incompressibility and the boundary conditions.
