Enhanced weakly-compressible MPS method for violent free-surface flows: Role of particle regularization techniques

Abstract

This paper develops a consistent particle method for capturing the highly non-linear behavior of violent free-surface flows, based on an Enhanced Weakly Compressible Moving Particle Semi-implicit (EWC-MPS) method. It pays special attention to the evaluation and improvement of two particle regularization techniques, namely, pairwise particle collision (PC) and particle shifting (PS). To improve the effectiveness of PC in removing noisy pressure field, and volume conservation issue of PS, we propose and evaluate several enhancements to these techniques, including a novel dynamic PC technique, and a consistent PS algorithm with new boundary treatments and additional terms (in the continuity and momentum equations).Besides, we introduce modified higher-order and anti-symmetric operators for the diffusive and shear force terms. Evaluation of the proposed developments for violent free-surface flow benchmark cases (2D dambreak, 3D water sloshing, and 3D dam-break with an obstacle) confirms an accurate prediction of the flow evolution and rigid body impact, as well as long-term stability of the simulations. The dynamic PC reduces pressure noises with low energy dissipation, and the consistent PS conserves the volume even for extreme deformations. Comparing the role of these new particle regularization techniques demonstrates the effectiveness of both in assuring the uniformity of the particle distribution and pressure fields; nevertheless, the implementation of PS is found to be more complex and time-consuming, mainly due to its need for free surface detection and boundary treatment with many tuning parameters.

A Review of SPH Techniques for Hydrodynamic Simulations of Ocean Energy Devices

“…Notwithstanding, it should be underlined that although the original version of PST and its variants show remarkable ability to cope with several challenging problems, their physical rationality could pose some limitations when being applied to realistic engineering problems. For instance, as reported by the extensive SPH literature (see, e.g., [155,157,158,160]), several versions of PST (see, e.g., [118,156]) could trigger the volume-non-conservation issue in simulating violent free-surface flows with long-term duration. This is caused by the fact that in these PST variants, after being repositioned, the particle positions are still updated according to an unchanged velocity field (i.e., non-Lagrangian transport velocity), which is nonphysical from a rigorous point of view.…”

“…After this pioneering work, PST has been further developed by the SPH community and applied to diverse problems, forming various PST variants in both the weakly compressible and truly incompressible senses (see e.g., [93,118,148,[151][152][153][154][155][156][157][158][159]). It is undeniable that PSTs can offer uniform particle distribution (i.e., better quality of particle distribution-see also Figure 10) and thus improve the numerical accuracy and stability of SPH simulations.…”

“…As a consequence, the accumulating errors on the potential energy gradually lead to the over-expansion (or over-compression when being subjected to negative pressures) of total fluid volume during simulations. Therefore, the SPH community have been struggling for making PST more physical in different ways, such as integrating the shifting velocity, δv, into the governing equations (see, e.g., [155,158]) and using a fully Arbitrary-Lagrangian-Eulerian (ALE) framework (see, e.g., [148,161]); these variants strongly improve the rationality and interpretability of PSTs through rigorous mathematical considerations, although they require modifying the existing codes to a large extent because of the more complex formalism of the governing equations. In addition to that, there have been simpler measures such as locally deactivating shifting when the fluid suffers from the volume-non-conservation issue [157] or introducing a corrective cohesion force to adaptively compensate the over-expansion/compression [160].…”

Fluid-driven granular dynamics through a consistent multi-resolution particle method

“…SPH and MPS have gone through significant developments to improve their accuracy and stability for highly dynamic and multiphase flows [22,23,24,25,26,27,28]. Shakibaeinia and Jin [29] introduced the weakly compressible MPS method (WC-MPS).…”

An Anti-Clustering Model for Stability Enhancement of a 3D Moving Particle Semi-Implicit Method and Two-Phase Coupling between MPS and Euler Grids

“…The fifth technique presents a scheme for Dynamic Stabilization [20,21], which meticulously reproduces adequate repulsive forces to attenuate the interparticle penetration and thus stabilizes the calculations. The sixth techniques is based on the regularization techniques (such as particle shifting and collision) [22][23][24][25][26]. On the other hand, the stability algorithm and application of SPH [27][28][29], which is also a meshless method, attracted the authors' attention, such as the high accuracy pressure model proposed by Zheng et al [30] and artificial viscosity model used by Monaghan et al and Daniel et al [31][32][33].…”