scholarly journals SPH Corrección de la deficienccia de límites para la mejora de condiciones de contornos en superficies deformables

2010 ◽  
Vol 4 (7) ◽  
pp. 21 ◽  
Author(s):  
Van Jones ◽  
Qing Yang ◽  
Leigh McCue-Weil
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Momentum Equation ◽  
Repulsive Force ◽  
Virtual Particles ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Cfd Method

Smoothed particle hydrodynamics (SPH) is a meshless, Lagrangian CFD method. SPH often utilizes static virtual particles to correct for integral deficiencies that occur near boundaries. These virtual particles, while useful in most cases, can be difficult to implement for objects which experience large deformations. As an alternative to virtual particles, a repulsive force algorithm is presented which loosely emulates the presence of virtual particles in the SPH momentum equation.

Modeling Hypervelocity Impacts Using Smoothed Particle Hydrodynamics

2018 ◽  
Author(s):  
M. Ganser ◽  
B. van der Linden ◽  
C. G. Giannopapa
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hypervelocity Impact ◽  
Density Fluctuations ◽  
Computational Domain ◽  
Simulation Tool ◽  
Hypervelocity Impacts ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Hypervelocity impacts occur in outer space where debris and micrometeorites with a velocity of 2 km/s endanger spacecraft and satellites. A proper shield design, e.g. a laminated structure, is necessary to increase the protection capabilities. High velocities result in massive damages. The resulting large deformations can hardly be tackled with mesh based discretization methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless scheme, can resolve large topological changes whereas it still follows the continuous formulation. Derived by variational principles, SPH is able to capture large density fluctuations associated with hypervelocity impacts correctly. Although the impact region is locally limited, a much bigger domain has to be discretized because of strong outgoing pressure waves. A truncation of the computational domain is preferable to save computational power, but this leads to artificial reflections which influence the real physics. In this paper, hypervelocity impact (HVI) is modelled by means of basic conservation assumptions leading to the Euler equations of fluid dynamics accompanied by the Mie-Grueneisen equation of state. The newly developed simulation tool SPHlab presented in this work utilizes the discretization method smoothed particle hydrodynamics (SPH) to capture large deformations. The model is validated through a number of test cases. Different approaches are presented for non-reflecting boundaries in order to tackle artificial reflections on a computational truncated domain. To simulate an HVI, the leading continuous equations are derived and the simulation tool SPHlab is developed. The method of characteristics allows to define proper boundary fluxes by removing the inwards travelling information. One- and two-dimensional model problems are examined which show excellent absorption behaviour. An hypervelocity impact into a laminated shield is simulated and analysed and a simple damage model is introduced to model a spallation failure mode.

scholarly journals An Efficient Sleepy Algorithm for Particle-Based Fluids

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xiao Nie ◽  
Leiting Chen ◽  
Tao Xiang
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Flow Behavior ◽  
Visual Quality ◽  
Repulsive Force ◽  
Performance Gain ◽  
Weakly Compressible ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Fluid Particles ◽  
Computational Resources

We present a novel Smoothed Particle Hydrodynamics (SPH) based algorithm for efficiently simulating compressible and weakly compressible particle fluids. Prior particle-based methods simulate all fluid particles; however, in many cases some particles appearing to be at rest can be safely ignored without notably affecting the fluid flow behavior. To identify these particles, a novel sleepy strategy is introduced. By utilizing this strategy, only a portion of the fluid particles requires computational resources; thus an obvious performance gain can be achieved. In addition, in order to resolve unphysical clumping issue due to tensile instability in SPH based methods, a new artificial repulsive force is provided. We demonstrate that our approach can be easily integrated with existing SPH based methods to improve the efficiency without sacrificing visual quality.

scholarly journals Simulation the deformation and damage of a rock massive containing a cavity

2020 ◽  
pp. 138-145
Author(s):  
Виталий Алексанрович Трофимов ◽  
Иван Евгеньевич Шиповский
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Economic Activity ◽  
Fracture Process ◽  
Strain State ◽  
Fracture Criterion ◽  
Large Deformations ◽  
Karst Formation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Accumulation Of Damage

Карстовые проявления широко распространены во многих регионах и представляют значительную опасность для проживания и хозяйственной деятельности. Воронки возникают при обрушении горных пород над подземными пустотами (пещерами, выработками и т.д.), образовавшимися при карстовом процессе или в результате антропогенного воздействия в массиве горных пород. Однако не каждая карстовая или техногенная полость приводит к разрушению земной поверхности, и, как правило, ее возникновение является неожиданным. В данной работе рассматривается динамика формирования провалов земной поверхности в виде карстовой воронки. Для этого с помощью бессеточного метода сглаженных частиц (SPH) решается геомеханическая задача. Выбранный численный метод позволяет получить решение задачи с учетом больших деформаций и возможных разрушений в процессе изменения напряженно-деформированного состояния. Используется критерий разрушения Друккера-Прагера, параметры которого со временем меняются в соответствии с накоплением повреждений, которые определяют временное развитие процесса разрушения, его начало и скорость. Karst manifestations are widespread in many regions and pose a significant danger to residence and economic activity. Failing funnels arise during the collapse of rocks over underground voids (caves, workings, etc.), formed during karst formation or in the process of anthropogenic doing in the rock massive. However, not every karst or technogenic cavity gives rise to a failure of the earth’s surface, and as a rule, its occurrence is unexpected. In this work, we consider the dynamics of the formation of dips of the earth’s surface in the form of a collapse pipe. To do this, the geomechanical problem is solved by the meshless code Smoothed Particle Hydrodynamics (SPH). The method allows to obtain a solution to the problem taking into account large deformations and possible discontinuities in the process of changing the stress-strain state. The Drucker-Prager fracture criterion is used, the parameters of which change over time in accordance with the accumulation of damage, which determines the temporary development of the fracture process, its beginning and speed.

A Comparison of Smoothed Particle Hydrodynamics (SPH) and Coupled SPH-FEM Methods for Modeling Machining

2020 ◽  
Author(s):  
Nishant Ojal ◽  
Harish P. Cherukuri ◽  
Tony L. Schmitz ◽  
Adam W. Jaycox
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Solid Mechanics ◽  
Large Deformations ◽  
Computational Time ◽  
Depth Of Cut ◽  
Fe Model ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle

Abstract Smoothed Particle Hydrodynamics (SPH), a particle-based, meshless method originally developed for modeling astrophysical problems, is being increasingly used for modeling fluid mechanics and solid mechanics problems. Due to its advantages over grid-based methods in the handling of large deformations and crack formation, the method is increasingly being applied to model material removal processes. However, SPH method is computationally expensive. One way to reduce the computational time is to partition the domain into two parts where, the SPH method is used in one segment undergoing large deformations and material separation and in the second segment, the conventional finite element (FE) mesh is used. In this work, the accuracy of this SPH-FEM approach is investigated in the context of orthogonal cutting. The high deformation zone (where chips form and curl) is meshed with the SPH method, while the rest of the workpiece is modeled using the FE method. At the interface, SPH particles are coupled with FE mesh for smooth transfer of stress and displacement. The boundary conditions are applied to tool and FE zone of the workpiece. For comparison purposes, a fully-SPH model (workpiece fully discretized by SPH) is also developed. This is followed by a comparison of the results from the coupled SPH-FE model with the SPH model. A comparison of the chip profile, the cutting force, the von Mises stress and the damage parameter show that the coupled SPH-FE model reproduces the SPH model results accurately. However, the SPH-FE model takes almost 40% less time to run, a significant gain over the SPH model. Similar reduction in computation time is observed for in a micro-cutting application (depth of cut of 300 nm). Based on these results, it is concluded that coupling SPH with FEM in machining models decreases simulation time significantly while still producing accurate results. This observation suggests that three-dimensional machining problems can be modeled using the combined SPH-FEM approach without sacrificing accuracies.

scholarly journals Investigation of the Configuration of Small Hydropower using a Novel Smoothed Particle Hydrodynamics Method

2021 ◽  
Vol 945 (1) ◽  
pp. 012039
Author(s):  
Shu Kai Ng ◽  
Akihiko Nakayama
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Vertical Axis ◽  
Fluid Structure Interactions ◽  
Small Hydropower ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Cfd Method

Abstract A novel Computational Fluid Dynamics (CFD) method utilizing Smoothed Particle Hydrodynamics (SPH) has been developed and applied to a simulation of flows in small hydropower systems. The simulation of the flow through a gravitational vortex turbine (GVT) small hydropower system where the flow is directed to a circular basin with a vertical-axis turbine, harnessing the rotational energy of the vortex formed to drive the turbine. Two modes of Fluid-Structure Interactions (FSI) were tested with identical flow conditions to evaluate the potential of this method to simulate complex FSI scenarios. It was found that simulation results for both one-way and two-way interactions produced reasonable results. The two-way interaction result proved to reflect more accurate FSI scenarios, but more studies are needed to provide validation.

Smoothed Particle Hydrodynamics for the Rising Pattern of Oil Droplets

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Mehdi Rostami Hosseinkhani ◽  
Pourya Omidvar
Keyword(s):  
Surface Tension ◽  
Smoothed Particle Hydrodynamics ◽  
Center Of Mass ◽  
Density Ratio ◽  
Momentum Equation ◽  
Oil Droplets ◽  
Two Phase ◽  
Droplet Shape ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

The problem of rising droplets in liquids is important in physics and has had many applications in industries. In the present study, the rising pattern of oil droplets has been examined using the smoothed particle hydrodynamics (SPH), which is a fully Lagrangian meshless method. The open-source SPHysics2D code is developed to two phase by adding the effects of surface tension and an added pressure term to the momentum equation. Several problems of droplet dynamics were simulated, and the performance of the developed code is evaluated. First, the still water–oil tank problem was solved to examine the hydrostatic pressure, especially at the interface, for different density ratios. Then, the rising patterns of an oil droplet of different densities are simulated and the time evolutions of the rising velocity and center of mass are shown. It is shown that the shape and behavior of the droplet rising depend on the balance between viscous, surface tension, and dynamic forces. Afterward, the flow morphologies of multiple droplet rising are shown where the density ratio causes negligible effects on the droplet shape, but it has large effects on the dynamics behavior of rising process.

Smoothed Particle Methods and Their Applicability to Tribology

2011 ◽  
Author(s):  
Jonathan P. Kyle ◽  
Elon J. Terrell
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hydrodynamic Lubrication ◽  
Particle Methods ◽  
Governing Equations ◽  
Problem Domain ◽  
Numerical Accuracy ◽  
Recent Interest ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

An in-house solver was created to simulate contact mechanics and hydrodynamic lubrication using smoothed particle hydrodynamics (SPH), SPH is a meshfree, particle-based method that can be used to solve continuum problems in solid and fluid mechanics. In this approach, the problem domain is represented by particles that move according to prescribed governing equations. Because smoothed particle methods have been shown to have the advantage of being able to model large deformations without concern of degradation in numerical accuracy, they have received recent interest for application to complex problems in tribology—the exploration of which is the focus of this study.

Smoothed Particle Hydrodynamics Applied to the Modelling of Landslides

2014 ◽  
Vol 553 ◽  
pp. 519-524 ◽  
Author(s):  
Vincent Lemiale ◽  
Laura Karantgis ◽  
Philip Broadbrige
Keyword(s):  
Natural Hazards ◽  
Smoothed Particle Hydrodynamics ◽  
Slope Failure ◽  
Large Deformations ◽  
A Priori ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Mesh Free Methods ◽  
Mechanism Of Failure

Landslides are among the most devastating natural hazards because they often initiate rapidly and mobilize very large volumes of material. While the mechanics of landslides is relatively well understood it is still extremely difficult to anticipate any particular event and estimate its potential consequences. Mesh-free methods are ideally suited to handle large deformations associated with slope failure but they often assume the mechanism of failure a priori. In this work we apply Smoothed Particle Hydrodynamics to simulate all phases of a landslide within one single numerical platform. A Drücker-Prager model is used to determine the onset of failure. The post-failure behaviour is accommodated naturally by the mesh-free nature of the method. The relevance of the method to the modelling of landslides is demonstrated on several examples of slope failure.

scholarly journals Factors Influencing Quasistatic Modeling of Deformation and Failure in Rock-Like Solids by the Smoothed Particle Hydrodynamics Method

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
X. W. Tang ◽  
Y. D. Zhou ◽  
Y. L. Liu
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Progressive Failure ◽  
Axial Stress ◽  
Failure Process ◽  
Momentum Equation ◽  
Sph Method ◽  
Deformation And Failure ◽  
Failure Evolution ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

As a Lagrangian mesh-free numerical method, the Smoothed Particle Hydrodynamics (SPH) method has been traditionally applied for modeling astrophysics, fluid flows and thermal problems, and there has been a growing interest in applying SPH to solid deformation problems. However, the potential of this method for quasistatic analysis of rock-like brittle materials has not been clearly explored. The major aim of this paper is to investigate the effects of key factors in SPH on the load-deformation response of rock-like solids, including variations in the particle approximation theory, the magnitude of the smoothing length and its variable method. Simple uniaxial compression (UC) loading conditions were chosen, and a series of numerical studies were carried out sequentially on an idealized elastic case and an actual test of marble material. Typical results of the axial stress-strain response from infinitesimal to finite deformation as well as the progressive failure process for the marble tests are given and the influences of various factors are discussed. It is found that only provided proper choices of particle momentum equation and the smoothing length parameter, the SPH method is capable for favorably reproducing the deformation and progressive failure evolution in rock-like materials under quasistatic compression loads.

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