Sloshing Simulation of Single-Phase and Two-Phase SPH using DualSPHysics

The sloshing phenomenon is one of the free surface flow that can endanger liquid cargo carriers such as ships. Sloshing is defined as the resonance of fluid inside a tank caused by external oscillation. When sloshing is close to the natural frequency of the tank it could endanger ships. Particle method has the advantages to be applied because sloshing is dealing with free surface. One of the particle methods is Smoothed Particle Hydrodynamics (SPH). In this study, compressible SPH was used as a result of the pressure oscillation, which exists because of the effect of density fluctuation as nature of weakly compressible SPH. To reduce pressure noise, a filtering method, Low Pass Filter, was used to overcome pressure oscillation. Three pressure sensors were used in the sloshing experiment with a combination of motions and filling ratios. Only one pressure sensor located in the bottom was used to validate the numerical results. A set of SPH parameters were derived that fit for the sloshing problem. The SPH results show a good agreement with the experiment’s. The difference between SPH and experiment is under 1 % for sway, but a larger difference shows in roll. Low pass filter technique could reduce pressure noise, but comprehensive method needs to develop for general implementation.

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Experiments on generation of surface waves by an underwater moving bottom

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2015.0069 ◽

2015 ◽

Vol 471 (2178) ◽

pp. 20150069 ◽

Cited By ~ 8

Author(s):

Timothée Jamin ◽

Leonardo Gordillo ◽

Gerardo Ruiz-Chavarría ◽

Michael Berhanu ◽

Eric Falcon

Keyword(s):

Free Surface ◽

Surface Waves ◽

Surface Deformation ◽

Fluid Layer ◽

Fluid Velocity ◽

Pass Filter ◽

Low Pass Filter ◽

Low Pass ◽

Spatio Temporal ◽

Experimental Findings

We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom undergoes an upward motion. Simultaneous measurements of the free-surface deformation and the fluid velocity field are focused on the role of the bottom kinematics (i.e. its spatio-temporal features) in wave generation. We observe that the fluid layer transfers bottom motion to the free surface as a temporal high-pass filter coupled with a spatial low-pass filter. Both filter effects are often neglected in tsunami warning systems, particularly in real-time forecast. Our results display good agreement with a prevailing linear theory without any parameter fitting. Based on our experimental findings, we provide a simple theoretical approach for modelling the rapid kinematics limit that is applicable even for initially non-flat bottoms: this may be a key step for more realistic varying bathymetry in tsunami scenarios.

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A physically consistent particle method for high-viscous free-surface flow calculation

Computational Particle Mechanics ◽

10.1007/s40571-021-00408-y ◽

2021 ◽

Author(s):

Masahiro Kondo ◽

Takahiro Fujiwara ◽

Issei Masaie ◽

Junichi Matsumoto

Keyword(s):

Angular Momentum ◽

Free Surface ◽

Particle Method ◽

Free Surface Flow ◽

Momentum Conservation ◽

Free Surface Flows ◽

Surface Flow ◽

Particle Methods ◽

Surface Flows ◽

Angular Momentum Conservation

AbstractParticle methods for high-viscous free-surface flows are of great use to capture flow behaviors which are intermediate between solid and liquid. In general, it is important for numerical methods to satisfy the fundamental laws of physics such as the conservation laws of mass and momentum and the thermodynamic laws. Especially, the angular momentum conservation is necessary to calculate rotational motion of high-viscous objects. However, most of the particle methods do not satisfy the physical laws in their spatially discretized system. The angular momentum conservation law is broken mostly because of the viscosity models, which may result in physically strange behavior when high-viscous free-surface flow is calculated. In this study, a physically consistent particle method for high-viscous free-surface flows is developed. The present method was verified, and its performance was shown with calculating flow in a rotating circular pipe, high-viscous Taylor–Couette flow, and offset collision of a high-viscous object.

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Application of background pressure with kinematic criterion for free surface extension to suppress non-physical voids in the finite volume particle method

10.31224/osf.io/3mpyt ◽

2019 ◽

Author(s):

Nathan Quinlan ◽

Mohsen Hassanzadeh Moghimi

Keyword(s):

Free Surface ◽

Finite Volume ◽

Particle Method ◽

Free Surface Flow ◽

Surface Flow ◽

Particle Methods ◽

Positive Pressure ◽

Absolute Pressure ◽

Free Surfaces ◽

Spatial Discretisation

Lagrangian particle methods such as smoothed particle hydrodynamics (SPH) and the finite volume particle method (FVPM) can suffer from non-physical voids in the spatial discretisation, due to the inability of numerical particles to deform as continuum fluid elements can. It is known that the situation can be improved for wall-bounded flows in SPH by adding a uniform background pressure to ensure positive absolute pressure everywhere. In this article, we investigate the application of background pressure in FVPM, and show that numerical voids grow under negative pressure and collapse under positive pressure. To use this technique in free-surface flow, however, the background pressure must be applied as an atmospheric pressure at the free surface. A kinematic criterion for free surface extension (KCFSE) to differentiate physical free surfaces from new numerical voids has been developed, supplementing the inherent capability of FVPM to identify free-surface particles robustly. The novel method enables background pressure to be applied at physical free surfaces and throughout the fluid, but not in non-physical voids, facilitating the suppression of such spurious voids. The KCFSE is validated for a translating square cylinder inside a rectangular numerical domain, with and without a free surface, and liquid in an oscillating rectangular tank.

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