Yuma Shimizu

Comparative study on accuracy and conservation properties of two particle regularization schemes and proposal of an optimized particle shifting scheme in ISPH context

Abstract The paper provides a comparative investigation on accuracy and conservation properties of two particle regularization schemes, namely, the Dynamic Stabilization (DS) [1] and generalized Particle Shifting (PS) [2] schemes in simulations of both internal and free-surface flows in ISPH (Incompressible SPH) context. The paper also presents an Optimized PS (OPS) scheme for accurate and consistent implementation of particle shifting for free-surface flows. In contrast to PS, the OPS does not contain any tuning parameters for free-surface, consistently resulting in perfect elimination of shifting normal to an interface and resolves the unphysical discontinuity beneath the interface, seen in PS results.

Numerical Investigation of the Morphological Dynamics of a Step-and-Pool Riverbed Using DEM-MPS

AbstractIn mountain streams, riverbeds with a series of coarse gravel steps are common. The sequence flow pattern with a chute and pool is usually formed on series of steps, where a transition regi...

An MPS-based particle method for simulation of multiphase flows characterized by high density ratios by incorporation of space potential particle concept

Abstract Simulation of multiphase flows characterized by high density ratios is targeted by using a refined particle method. The proposed method is founded on Moving Particle Semi-implicit (MPS) method which is a projection-based particle method. The proposed method comprises of a decoupled two-step computational algorithm through application of a consistent scheme for coupling the light/heavy phases by incorporating the concept of Space Potential Particles (SPP). The proposed coupling scheme guarantees the continuity of pressure and space (volume conservation) at the phase interface without any need for commonly applied density smoothing/averaging schemes or application of numerical stabilizing terms. Verification of the proposed multiphase particle method is conducted through the simulations of four benchmark tests and the method is shown to possess acceptable accuracy and convergence properties.

An enhanced ISPH–SPH coupled method for simulation of incompressible fluid–elastic structure interactions

Abstract An enhanced fully-Lagrangian meshfree computational method is developed for simulating incompressible fluid–elastic structure interactions. The developed method corresponds to a SPH (Smoothed Particle Hydrodynamics)-based coupled FSI (Fluid–Structure Interaction) solver. Coupling is conducted in between a projection-based ISPH (Incompressible SPH) fluid model and a newly developed SPH-based structure model in a mathematically–physically consistent manner. Fluid model is founded on the solution of Navier–Stokes and continuity equations while structure model is set on conservation laws for linear and angular momenta corresponding to an isotropic elastic solid. A set of previously developed enhanced schemes are incorporated for the ISPH fluid model, hence, the developed coupled method is referred to as Enhanced ISPH–SPH. The performance of SPH-based structure model is first validated in reproduction of benchmark tests including dynamic response of a free oscillating cantilever plate and stress distribution inside an isotropic plate with a circular opening. Then the Enhanced ISPH–SPH is scrupulously verified through simulations of FSI problems including hydrostatic water column on an elastic plate, dam break with an elastic gate, sloshing in tanks with elastic baffles and hydroelastic slammings of an elastic aluminum wedge and a marine panel. To the best knowledge of the authors, this paper presents the first semi-implicit/explicit ISPH–SPH coupled method for FSI related to deformable elastic structures with comprehensive validations and performance investigations.