Cylindrical Smoothed Particle Hydrodynamics Simulations of Water Entry

This paper presents a smoothed particle hydrodynamics (SPH) modeling technique based on the cylindrical coordinates for axisymmetrical hydrodynamic applications, thus to avoid a full three-dimensional (3D) numerical scheme as required in the Cartesian coordinates. In this model, the governing equations are solved in an axisymmetric form and the SPH approximations are modified into a two-dimensional cylindrical space. The proposed SPH model is first validated by a dam-break flow induced by the collapse of a cylindrical column of water with different water height to semi-base ratios. Then, the model is used to two benchmark water entry problems, i.e., cylindrical disk and circular sphere entry. In both cases, the model results are favorably compared with the experimental data. The convergence of model is demonstrated by comparing with the different particle resolutions. Besides, the accuracy and efficiency of the present cylindrical SPH are also compared with a fully 3D SPH computation. Extensive discussions are made on the water surface, velocity, and pressure fields to demonstrate the robust modeling results of the cylindrical SPH.

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Smoothed Particle Hydrodynamics Simulations of Whole Blood in Three-Dimensional Shear Flow

International Journal of Computational Methods ◽

10.1142/s0219876220500097 ◽

2020 ◽

Vol 17 (10) ◽

pp. 2050009

Author(s):

Sisi Tan ◽

Mingze Xu

Keyword(s):

Shear Flow ◽

Smoothed Particle Hydrodynamics ◽

Whole Blood ◽

Blood Cells ◽

White Blood Cells ◽

Three Dimensional ◽

Immersed Boundary ◽

Particle Hydrodynamics ◽

Sph Model ◽

Smoothed Particle

Numerical modeling of whole blood still faces great challenges although significant progress has been achieved in recent decades, because of the large differences of physical and geometric properties among blood components, including red blood cells (RBCs), platelets (PLTs) and white blood cells (WBCs). In this work, we develop a three-dimensional (3D) smoothed particle hydrodynamics (SPH) model to study the whole blood in shear flow. The immersed boundary method (IBM) is used to deal with the interaction between the fluid and cells, which provides a possibility to model the RBCs, PLTs and WBCs simultaneously. The deformation of a small capsule, comparable to a PLT in size, is first examined to show the feasibility of SPH model for the PLTs’ behaviors. The motion of a single RBC in shear flow is then studied, and three typical modes, tank-treading, swinging and tumbling motions, are reproduced, which further confirm the reliability of the SPH model. After that, a simulation of the whole blood in shear flow is carried out, in which the margination trend is observed for both PLTs and WBC. This shows the capability of SPH model with IBM for the simulation of whole blood.

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PARTICLE MESH HYDRODYNAMICS FOR ASTROPHYSICS SIMULATIONS

International Journal of Modern Physics C ◽

10.1142/s0129183107010851 ◽

2007 ◽

Vol 18 (04) ◽

pp. 610-618 ◽

Cited By ~ 8

Author(s):

PHILIPPE CHATELAIN ◽

GEORGES-HENRI COTTET ◽

PETROS KOUMOUTSAKOS

Keyword(s):

Smoothed Particle Hydrodynamics ◽

Three Dimensional ◽

Particle Method ◽

Compressible Euler Equations ◽

Particle Interactions ◽

Governing Equations ◽

Compressible Euler ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

High Order Interpolation

We present a particle method for the simulation of three dimensional compressible hydrodynamics based on a hybrid Particle-Mesh discretization of the governing equations. The method is rooted on the regularization of particle locations as in remeshed Smoothed Particle Hydrodynamics (rSPH). The rSPH method was recently introduced to remedy problems associated with the distortion of computational elements in SPH, by periodically re-initializing the particle positions and by using high order interpolation kernels. In the PMH formulation, the particles solely handle the convective part of the compressible Euler equations. The particle quantities are then interpolated onto a mesh, where the pressure terms are computed. PMH, like SPH, is free of the convection CFL condition while at the same time it is more efficient as derivatives are computed on a mesh rather than particle-particle interactions. PMH does not detract from the adaptive character of SPH and allows for control of its accuracy. We present simulations of a benchmark astrophysics problem demonstrating the capabilities of this approach.

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Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽

10.3390/w11112314 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2314 ◽

Cited By ~ 4

Author(s):

Shu Wang ◽

Anping Shu ◽

Matteo Rubinato ◽

Mengyao Wang ◽

Jiping Qin

Keyword(s):

Debris Flow ◽

Water Content ◽

Smoothed Particle Hydrodynamics ◽

Debris Flows ◽

Sph Method ◽

Particle Hydrodynamics ◽

Sph Model ◽

Smoothed Particle ◽

The Impact ◽

Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

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