Improvement of pressure distribution to arbitrary geometry with boundary condition represented by polygons in particle method

Abstract

The boundary condition represented by polygons in the moving particle semi-implicit method can accurately represent geometries and treat complex geometry with high efficiency. However, inaccurate wall contribution to the Poisson's equation leads to drastic numerical oscillation. To address this issue, in this research, we analyzed the problems of the Poisson's equation used in the boundary condition represented by polygons. The new Poisson's equation is proposed based on the improved source term (Tanaka and Masunaga, Trans Jpn Soc Comput Eng Sci, 2008). The asymmetric gradient model (Khayyer and Gotoh, Coastal Engineering Journal, 2008) is also adopted to further suppress the numerical oscillation of fluid particles. The proposed method can dramatically improve the pressure distribution to arbitrary geometry in three dimensions and keep the efficiency. Four examples including the hydrostatic simulation, dam break simulation, and two complex geometries are verified to show the general applicability of the proposed method. Figure 17. Snapshots of the pressure distribution in a water tank with a wedge at t = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 s. Figure 20. Snapshots of the complex geometry at t = 0.05, 0.09, 0.14, 0.16, and 0.18 s.

Two-Way Coupling Simulation of Fluid-Multibody Dynamics for Estimating Power Generation Performance of Point Absorber Wave Energy Converters

“…To solve this problem, it is necessary to further investigate the particle arrangement and related boundary conditions for arbitrary complex shapes in future research. In this regard, several recent studies [45,46] have been reported by researchers employing the particle method. Second, as shown in Figure 29, when the wave elevation time series is compared at a 1 m point in front of the RM3 structure depending on the presence or absence of RM3, a WEC structure, it is observed that the elevation of the incoming waves decreases by approximately 3.3% owing to the waves diffracted by the WEC structure.…”