A novel ghost cell boundary model for the explicit moving particle simulation method in two dimensions

The moving particle simulation (MPS) method has proved to be an effective technique to model fluid flows with free surfaces. However, it still remains a challenging task to treat the wall boundary problem with complicated geometries accurately and robustly. The purpose of this work is to propose a two-dimensional ghost cell boundary model for the explicit MPS method to achieve this end. The appeal of the novel model lies in providing an easy and natural treatment for the wall boundary of complicated shapes. On one hand, the wall boundary can be easily represented by using ghost cells of different sizes or shapes (e.g. triangles and quadrilaterals in two dimensions), and ghost cells are constructed in the pre-processing phase. On the other hand, the particle-cell interaction can be modeled by an integral version of the MPS model that requires the specific area of each cell, while the particle-particle interaction near wall boundary is still handled by the conventional version of the MPS model via assuming that each particle takes the same area. In this manner, the particle-cell interaction is modeled naturally. Two numerical examples, i.e. the hydrostatic and dam break tests, are performed to validate the effectiveness of the proposed model, where the effects of the distribution of ghost cells are also numerically investigated. Finally, a numerical case considering a star-shaped obstacle in dam break flows is carried out to demonstrate the capacity of the novel model in dealing with the wall boundary problem with complicated geometries.