Proposed Smoothed Particle Hydrodynamics Model Research Articles

A Development of a SPH Model for Simulating Surface Erosion by Impact(s) of Irregularly Shaped Particles

Modeling and studying the impact of angular particles are very helpful in understanding the fundamental mechanisms of erosive wear. However, the majority of previous studies focused on well-defined symmetrical particles, which are not well representative of the abrasive particles. Hence, this study develops a mesh-free model based on the smoothed particle hydrodynamics (SPH) method to simulate impact(s) of single and multiple irregularly shaped particles on ductile material. A novel procedure is proposed to model the particle as a polygonal rigid body through measuring the corner vertices. Simulations are carried out by varying the input conditions and by using different types of angular particles. Common erosion mechanisms such as cutting, machining, ploughing, prying-off are successfully reproduced by the model. The predicted crater is compared with available experimental data, and good agreement has been achieved. The proposed SPH model and out present study could be useful in the study of erosive wear on the surface of metal devices that carries granular substances.

SPH Modelling of Sea-ice Pack Dynamics

Abstract The paper is concerned with the problem of sea-ice pack motion and deformation under the action of wind and water currents. Differential equations describing the dynamics of ice, with its very distinct mateFfigrial responses in converging and diverging flows, express the mass and linear momentum balances on the horizontal plane (the free surface of the ocean). These equations are solved by the fully Lagrangian method of smoothed particle hydrodynamics (SPH). Assuming that the ice behaviour can be approximated by a non-linearly viscous rheology, the proposed SPH model has been used to simulate the evolution of a sea-ice pack driven by wind drag stresses. The results of numerical simulations illustrate the evolution of an ice pack, including variations in ice thickness and ice area fraction in space and time. The effects of different initial ice pack configurations and of different conditions assumed at the coast-ice interface are examined. In particular, the SPH model is applied to a pack flow driven by a vortex wind to demonstrate how well the Lagrangian formulation can capture large deformations and displacements of sea ice.

Simulation of particle-laden flow in a Humphrey spiral concentrator using dust-liquid smoothed particle hydrodynamics

This paper demonstrates that our extended smoothed particle hydrodynamics (SPH) model can successfully simulate multiphase flow in a Humphrey spiral concentrator (HSC) with two phases: powder and water. The powder phase in the model was assumed to be a continuum, as the spacing between particles in this state is much smaller than the typical length scale of flow. Further investigation was conducted on the influences of various design factors of the HSC, including the descent angle and curvature profile of the trough, during the separation of a binary mineral particle mixture.The model was validated by comparing the simulated results with the experimental results of Loveday and Cilliers (1994) as well as those of a novel lab-scale-experiment using a miniature of the HSC. The proposed SPH model accurately simulated dusty liquid flow in the HSC in both cases with an acceptable degree of accuracy relative to the experimental results. These studies are expected to be useful in future optimizations of HSC design and operating conditions.

Numerical Study of Impact Behaviors of Angular Particles on Metallic Surface Using Smoothed Particle Hydrodynamics

ABSTRACTModeling and studying the impact behaviors of angular particles is critical in understanding the mechanisms of erosive wear on solid surfaces. This article focuses on effective mesh-free model based on the smoothed particle hydrodynamics (SPH) method to simulate impacts of angular particles on metallic surfaces. The predicted results are compared with the available experimental data, and good agreement has been achieved. Our simulations under different incident conditions successfully reproduce the general impact behaviors of angular particles, including rotating behavior and rebound behavior, which enables detailed examinations of erosion mechanisms. We find that the rotating behaviors are mainly determined by initial orientation and impact angle, whereas impact velocity has little effect. For backward impact involving a prying-off action, there generally exsits a critical impact velocity below which the cutting process would never be finished, which may result in a rebound angle greater than 90°. Further, multiple and overlapping impacts are simulated to reveal the effect of a pre-created crater on the subsequent impact. The results demonstrate the ability of the present model to handle the extremely deformed surface by overlapping impacts. The proposed SPH model and the present study could be useful in the study of erosive wear on the surface of metal devices that carry granular substances.

Numerical analysis on seepage failures of dike due to water level-up and rainfall using a water–soil-coupled smoothed particle hydrodynamics model

For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall.

SPH modeling of plane jets into water bodies through an inflow/outflow algorithm

This paper deals with the development and application of a two-dimensional weakly compressible Smoothed Particle Hydrodynamics (SPH) model to study plane jets propagating into still fluid tanks and current flows. These flow processes occurring in different water bodies are here treated through an appropriate algorithm to model inlet/outlet boundary conditions which are defined by different sets of particles. SPH equations of fluid mechanics including viscous and interface stabilization terms are adopted to determine the flow field induced by the fluid interaction. Flow phenomena induced by jet injection in a water body occur in natural and anthropic environments such as pollutant discharge into reservoirs, rivers and coasts, or in several engineering applications such as marine outfalls. Three test cases with different initial configurations are simulated: injection of a jet at the top and at the bottom of a water tank, and upstream of a channel flow (coflow jet). The proposed SPH model is validated both near the jet nozzle and far from it, comparing the obtained jet trajectories, widths and velocities with other numerical approaches, laboratory experiments and analytical solutions.

A Particle Model for Prediction of Cement Infiltration of Cancellous Bone in Osteoporotic Bone Augmentation

Femoroplasty is a potential preventive treatment for osteoporotic hip fractures. It involves augmenting mechanical properties of the femur by injecting Polymethylmethacrylate (PMMA) bone cement. To reduce the risks involved and maximize the outcome, however, the procedure needs to be carefully planned and executed. An important part of the planning system is predicting infiltration of cement into the porous medium of cancellous bone. We used the method of Smoothed Particle Hydrodynamics (SPH) to model the flow of PMMA inside porous media. We modified the standard formulation of SPH to incorporate the extreme viscosities associated with bone cement. Darcy creeping flow of fluids through isotropic porous media was simulated and the results were compared with those reported in the literature. Further validation involved injecting PMMA cement inside porous foam blocks — osteoporotic cancellous bone surrogates — and simulating the injections using our proposed SPH model. Millimeter accuracy was obtained in comparing the simulated and actual cement shapes. Also, strong correlations were found between the simulated and the experimental data of spreading distance (R2 = 0.86) and normalized pressure (R2 = 0.90). Results suggest that the proposed model is suitable for use in an osteoporotic femoral augmentation planning framework.

Smoothed particle hydrodynamics non-Newtonian model for ice-sheet and ice-shelf dynamics

We propose a new three-dimensional smoothed particle hydrodynamics (SPH) non-Newtonian model to study coupled ice-sheet and ice-shelf dynamics. Most existing ice-sheet numerical models use grid-based Eulerian discretizations, and are usually restricted to shallow ice-sheet and ice-shelf approximations of the momentum- conservation equation. SPH, a fully Lagrangian particle method, solves the full momentum-conservation equation. Numerical accuracy of the proposed SPH model is first verified by simulating Poiseuille flow, a plane shear flow with a free surface and the propagation of a blob of ice along a horizontal surface. Next, the SPH model is used to investigate the grounding-line dynamics of a ice sheet/shelf. The steady position of the grounding line, obtained from our SPH simulations, is in good agreement with laboratory observations for a wide range of bedrock slopes, ice-to-fluid density ratios, and flux. We examine the effect of non-Newtonian behavior of ice on the grounding-line dynamics. The non-Newtonian constitutive model is based on Glen’s law for a creeping flow of a polycrystalline ice. Finally, we investigate the effect of a bedrock geometry on a steady-state position of the grounding line.

SPH simulation of solitary wave interaction with a curtain-type breakwater

An incompressible Smoothed Particle Hydrodynamics (SPH) method is put forward to simulate non-linear and dispersive solitary wave reflection and transmission characteristics after interacting with a partially immersed curtain-type breakwater. The Naviers-Stokes equations in Lagrangian form are solved using a two-step split method. The method first integrates the velocity field in time without enforcing incompressibility. Then the resulting deviation of particle density is projected into a divergence-free space to satisfy incompressibility by solving a pressure Poisson equation. Basic SPH formulations are employed for the discretization of relevant gradient and divergence operators in the governing equations. The curtain wall and horizontal bottom are also numerically treated by fixed wall particles and the free surface of wave is tracked by particles with a lower density as compared with inner particles. The proposed SPH model is first verified by the test of a solitary wave with different amplitudes running against a vertical wall without opening underneath. Then it is applied to simulate solitary wave interacting with a partially immersed curtain wall with different immersion depths. The characteristics of wave reflection, transmission, dissipation and impacting forces on the curtain breakwater are discussed based on computational results.