In marine engineering, it is prone to encounter free surface flow problems. Typically, a boat moving on water causes nonlinear free surface flows accompanied by spray. A high-speed boat, in particular, experiences considerable resistance due to the spray, and some high-speed boats such as seaplanes and hovercrafts suffer great damage in their propulsion systems. Thus, predicting nonlinear free surface flow is an important issue for developing high-speed boats with high performance.
For the simulation of free surface flows, some computational fluid dynamics approaches called mesh-based method have been proposed. These methods are suitable for the flow of low-speed boats but not suitable for high-speed boats.
Other approaches called mesh-free method or particle method have been proposed for free surface flows. Moving particle semi-implicit (MPS), smoothed particle hydrodynamics (SPH) and particle finite element method (PFEM) are typical mesh-free methods widely used for nonlinear free surface flows. In many studies, mesh-free methods have been applied successfully to lots of problems in the marine engineering field.
Pak Chol Jun, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has proposed an improved MPS method with some modifications for simulating the flow around a moving body. To improve the original MPS method, he proposed the intermediate velocity of wall particles, Laplacian compensation in the domain close to the boundary, a technique to prevent fluid particles from penetrating the wall boundary, and a handling technique for the open boundary.
He applied the improved MPS method to hydrostatic pressure and sloshing problems to validate its performance. The comparison of the numerical results with the analytical results and experimental data showed that Laplacian compensation remarkably enhances the accuracy of MPS method.