Smoothed Particle Hydrodynamics Methodology Research Articles

Prediction modeling of coastal sediment transport using accelerated smooth particle hydrodynamics approach

A GPU-accelerated 3D smooth particle hydrodynamics (SPH) scheme is developed and applied to a coastal multi-phase liquid-sediment interaction and sediment transport. The SPH scheme's meshless design and the sediment's particle structure enable the modeling of the waves' interactions with the sediment particles beyond the limitation of the mesh-based methods. A Newtonian constitutive model is used to model the liquid phase, and the sediment transport is formulated based on the Herschel-Bulkley-Papanastasiou (HBP) model. The yield characteristics of the sediment phase are estimated using the Drucker-Prager yield criterion. Due to the parallelization of the solution on graphics processing units, the 3D SPH scheme's performance, which uses millions of particles, is improved. Good correlations were observed in the SPH predictions and experimental measurements, with a maximum difference of 4.85 %. The validated scheme is applied to formulate forecasting models for the coastline sediment transport. It is found that erosion and scouring are expected at the coastline region inclined to the direction of the sea waves, with a predicted mass erosion of about 60e3 kg in four years. The wave's velocity is also established to be directly proportional to the sediment transport. The proposed multi-phase SPH methodology is proven effective for sediment transport prediction.

Numerical investigation of turbulent lid-driven flow using weakly compressible smoothed particle hydrodynamics CFD code with standard and dynamic LES models

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian computational fluid dynamics method that has been widely used in the analysis of physical phenomena characterized by large deformation or multi-phase flow analysis, including free surface. Despite the recent implementation of eddy-viscosity models in SPH methodology, sophisticated turbulent analysis using Lagrangian methodology has been limited due to the lack of computational performance and numerical consistency. In this study, we implement the standard and dynamic Smagorinsky model and dynamic Vreman model as sub-particle scale models based on a weakly compressible SPH solver. The large eddy simulation method is numerically identical to the spatial discretization method of smoothed particle dynamics, enabling the intuitive implementation of the turbulence model. Furthermore, there is no additional filtering process required for physical variables since the sub-grid scale filtering is inherently processed in the kernel interpolation. We simulate lid-driven flow under transition and turbulent conditions as a benchmark. The simulation results show that the dynamic Vreman model produces consistent results with experimental and numerical research regarding Reynolds averaged physical quantities and flow structure. Spectral analysis also confirms that it is possible to analyze turbulent eddies with a smaller length scale using the dynamic Vreman model with the same particle size.

Numerical Simulation of Detonation and Brisance Performance of Aluminized HMX Using Density‐Adaptive SPH

AbstractThe prediction of the brisance performance of the aluminized explosive detonation, which involves complicated multiphase and multiphysics flow, is a difficult problem to tackle. In this paper, the detonation and brisance performance of aluminized HMX explosives is investigated using the density‐adaptive smoothed particle hydrodynamics methodology. The ignition and growth model was incorporated in smoothed particle hydrodynamics to calculate the pressure generated by the detonation of aluminized explosive, and the after‐burning combustion model was used to obtain the released energy caused by the combustion of aluminium particles. The elastic‐perfectly plastic model and Tillotson equation of state were employed to predict the dynamic behavior of metal material. In addition, the density‐adaptive method is employed to deal with the multiphase interface with a large density ratio. Firstly, the equations of state and constitutive models are verified by two benchmark cases, namely three‐dimensional detonation of PBX 9501 explosive and three‐dimensional aluminium‐aluminium high‐velocity impact. Subsequently, the detonation velocity and peak pressure of aluminized HMX with different mass fractions of aluminium powder are investigated. In the end, the interaction between the steel confiner and the detonation of aluminized explosive is conducted in order to study the brisance performance of aluminized explosive. The numerical results obtained from smoothed particle hydrodynamics are in good agreement with the experimental data, which shows that the detonation and the ballistic performance of the condensed explosive can be captured by density‐adaptive smoothed particle hydrodynamics very well.

A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

The faults in welding design and process every so often yield defective parts during friction stir welding (FSW). The development of numerical approaches including the finite element method (FEM) provides a way to draw a process paradigm before any physical implementation. It is not practical to simulate all possible designs to identify the optimal FSW practice due to the inefficiency associated with concurrent modeling of material flow and heat dissipation throughout the FSW. This study intends to develop a computational workflow based on the mesh-free FEM framework named smoothed particle hydrodynamics (SPH) which was integrated with adaptive neuro-fuzzy inference system (ANFIS) to evaluate the residual stress in the FSW process. An integrated SPH and ANFIS methodology was established and the well-trained ANIS was then used to predict how the FSW process depends on its parameters. To verify the SPH calculation, an itemized FSW case was performed on AZ91 Mg alloy and the induced residual stress was measured by ultrasonic testing. The suggested methodology can efficiently predict the residual stress distribution throughout friction stir welding of AZ91 alloy.

GPU-accelerated smoothed particle hydrodynamics modeling of jet formation and penetration capability of shaped charges

The prediction of the penetration of three-dimensional (3D) shaped charge into steel plates is a challenging task. In this paper, the smoothed particle hydrodynamics (SPH) method is applied to simulate the jet formation generated by the shaped charge detonation and its damage to steel plates. The Jones–Wilkins–Lee (JWL) equation of state (EOS), Tillotson EOS, and elastic–perfectly plastic constitutive model were incorporated into SPH for the modeling of explosive detonation and dynamic behavior of metal material. The compute unified device architecture (CUDA) parallel programming interface has been employed in SPH to improve the computational efficiency of SPH. Firstly, the constitutive models and EOSs are validated by 3D TNT slab detonation and aluminum–aluminum (Al–Al) high velocity impact. Then the jet formation of the shaped charge detonation and its penetration into the steel plates are investigated using the graphics processing unit (GPU)-accelerated SPH methodology. The numerical results of these test cases are compared against the published experimental data or analytical result, which shows that the GPU-accelerated SPH methodology is capable of tackling the 3D shaped charge detonation and penetration involving millions of particles with high computational efficiency.

An efficient SPH methodology for modelling mechanical characteristics of particulate composites

Particulate composites are one of the widely used materials in producing numerous state-of-the-art components in biomedical, automobile, aerospace including defence technology. Variety of modelling techniques have been adopted in the past to model mechanical behaviour of particulate composites. Due to their favourable properties, particle-based methods provide a convenient platform to model failure or fracture of these composites. Smooth particle hydrodynamics (SPH) is one of such methods which demonstrate excellent potential for modelling failure or fracture of particulate composites in a Lagrangian setting. One of the major challenges in using SPH method for modelling composite materials depends on accurate and efficient way to treat interface and boundary conditions. In this paper, a master-slave method based multi-freedom constraints is proposed to impose essential boundary conditions and interfacial displacement constraints in modelling mechanical behaviour of composite materials using SPH method. The proposed methodology enforces the above constraints more accurately and requires only smaller condition number for system stiffness matrix than the procedures based on typical penalty function approach. A minimum cut-off value-based error criteria is employed to improve the computational efficiency of the proposed methodology. In addition, the proposed method is further enhanced by adopting a modified numerical interpolation scheme along the boundary to increase the accuracy and computational efficiency. The numerical examples demonstrate that the proposed master-slave approach yields better accuracy in enforcing displacement constraints and requires approximately the same computational time as that of penalty method.

GPU-accelerated smoothed particle hydrodynamics modeling of granular flow

In this paper, the dynamical behavior of granular media is investigated numerically using smoothed particle hydrodynamics (SPH) with an elastoplastic and a phase-change constitutive model. A GPU-accelerated SPH code for granular flow modeling is implemented and validated using four test cases: (1) the collapse of an axisymmetric sand pile; (2) the impact force of sand on a rigid wall; (3) the head-on collisions of dense granular jets; and, (4) the impact of a granular jet with a wave structure on the granular film. The results of SPH simulations with the two models are compared to available experimental and numerical results. The validation showed that the dynamics of granular media are well predicted using the SPH methodology with an appropriate material model. An SPH simulation of granular flow run on a rather outdated GPU was already about 160 times as efficient as the same simulation run on a mainstream single CPU.

3D gradient corrected SPH for fully resolved particle–fluid interactions

Fully resolved fluid–solid coupling is explored with the gradient corrected weakly compressible SPH methodology being used to simulate an incompressible Newtonian fluid as well as being used to obtain the coupling force information required to accurately represent these interactions. Gradient correction allows for the application of the Neumann boundary condition required to describe the pressure fields at solid interfaces, as well as symmetry boundary conditions for velocity (where applicable) without the use of ghost or mirrored particles. A scaling study is performed by investigating the drag on an infinitely long cylinder at different smoothed particle hydrodynamics (SPH) resolutions, with finer resolution scales showing good correlation to other studies. The drag characteristics of several particle shapes and topologies are also investigated making use of both convex and non-convex particle shapes. Clear distinction for both the fluid and solid particle responses for the various solid particle shapes are observed. Boundary effects are also explored with results showing a strong responses to changing domain geometry aspect ratios. A many particle system with two different particle shapes are simulated to investigate bulk behaviour of the different solids falling under gravity in a fluid. All results presented in this paper are obtained from full 3D simulations.

Hypervelocity impact response of CFRP laminates using smoothed particle hydrodynamics method: Implementation and validation

The current work investigates the hypervelocity impact response (HVI) of carbon fiber reinforced polymer composites (CFRP) and the produced secondary debris using smoothed-particle hydrodynamics methodology (SPH) in LS-DYNA. The aim of present study is to reproduce numerically the CFRP material response to hypervelocity impact and fragments cloud, to investigate the applicability of SPH modeling technique on composite materials and to determine the suitable numerical solution parameters. A verification procedure for modeling of composite laminate using SPH methodology is proposed. The investigation starts with baseline quasi-static tests, and the results are compared against the available theoretical ones to ensure the stability and efficiency of the SPH kernel function under quasi-static loading. Afterwards, the developed methodology is applied to hypervelocity impact response of CFRPs and the ballistic limit, the crater diameter as well as the secondary debris cloud are numerically calculated and correlated to the published HVI experimental results on CFRP plates.

Accuracy analysis of SPH for flow in a model extruder with a kneading element

The Smoothed Particle Hydrodynamics (SPH) method is used to determine the flow through a model screw extruder at low Reynolds number with an emphasis on resolving the flow in narrow gaps, which are known to produce high shear rates and generate large temperatures. Firstly we demonstrate the validity of the SPH methodology by comparison on simple flows with known analytic solutions. We find excellent agreement and this also allows us to estimate the SPH particle size that is required to obtain accurate solutions for these and more complex flows. SPH simulations on a model single screw extruder with a kneading element are then compared with FEM solutions. Once again excellent agreement is achieved. Finally we demonstrate the SPH method on a model twin screw extruder, which is shown to be robust and qualitatively valid. In general these results show that SPH will be an important computational tool to investigate flows in similar devices.

Numerical Simulation of Shear Slitting Process of Grain Oriented Silicon Steel using SPH Method

Abstract Mechanical cutting allows separating of sheet material at low cost and therefore remains the most popular way to produce laminations for electrical machines and transformers. However, recent investigations revealed the deteriorating effect of cutting on the magnetic properties of the material close to the cut edge. The deformations generate elastic stresses in zones adjacent to the area of plastically deformed and strongly affect the magnetic properties. The knowledge about residual stresses is necessary in designing the process. This paper presents the new apprach of modeling residual stresses induced in shear slitting of grain oriented electrical steel using mesh-free method. The applications of SPH (Smoothed Particle Hydrodynamics) methodology to the simulation and analysis of 3D shear slitting process is presented. In experimental studies, an advanced vision-based technology based on digital image correlation (DIC) for monitoring the cutting process is used.

Simulation of self-compacting concrete in an L-box using smooth particle hydrodynamics

The three-dimensional Lagrangian-particle-based smooth particle hydrodynamics methodology was used to simulate the flow characteristics of self-compacting concrete (SCC) mixes in an L-box test. A Bingham-type constitutive model was coupled with the Lagrangian momentum and continuity equations to simulate the flow. The simulations of SCC focused on the flow times, the free-surface profile and the distribution of large aggregates (larger than or equal to 8 mm) during the flow. The numerical simulation results were compared with actual L-box tests carried out on several SCC mixes. The comparison revealed that the methodology is very well suited to predicting the flow behaviour of SCC in terms of passing and filling abilities and the distribution of large aggregates.

Smoothed Particle Hydrodynamics (SPH) modelling of transient heat transfer in pulsed laser ablation of Al and associated free-surface problems

A Smoothed Particle Hydrodynamics (SPH) numerical model is developed to simulate pulsed-laser ablation processes for micro-machining. Heat diffusion behaviour of a specimen under the action of nanosecond pulsed lasers can be described analytically by using complementary error function solutions of second-order differential equations. However, their application is limited to cases without loss of material at the surface. Compared to conventional mesh-based techniques, as a novel meshless simulation method, SPH is ideally suited to applications with highly non-linear and explosive behaviour in laser ablation. However, little is known about the suitability of using SPH for the modelling of laser-material interactions with multiple phases at the micro scale. The present work investigates SPH modelling of pulsed-laser ablation of aluminium where the laser is applied directly to the free-surface boundary of the specimen. Having first assessed the performance of standard SPH surface treatments for functions commonly used to describe laser heating, the heat conduction behaviour of a new SPH methodology is then evaluated through a number of test cases for single- and multiple-pulse laser heating of aluminium showing excellent agreement when compared with an analytical solution. Simulation of real ablation processes, however, requires the model to capture the removal of material from the surface and its subsequent effects on the laser heating process. Hence, the SPH model for describing the transient behaviour of nanosecond laser ablation is validated with a number of experimental and reference results reported in the literature. The SPH model successfully predicts the material ablation depth profiles over a wide range of laser fluences 4–23J/cm2 and pulse durations 6–10ns, and also predicts the transient behaviour of the ejected material during the laser ablation process. Unlike conventional mesh-based methods, the SPH model was not only able to provide the thermo-physical properties of the ejected particles, but also the effect of the interaction between them as well as the direction and the pattern of the ejection.

The application of the smoothed particle hydrodynamics (SPH) method to the simulation and analysis of blanking process

In this paper, the applications of mesh-free SPH (Smoothed Particle Hydrodynamics) methodology to the simulation and analysis of 3-D blanking process is presented. This approach allows for a complex analysis of physical phenomena occurring during the process without significant deterioration in the quality of the finite element mesh during large deformation. This allows for accurate representation of the loss of cohesion of the material under the influence of punch and cutting plate. An analysis of state of stress, strain and fracture mechanisms of the material is presented. In experimental studies, an advanced vision-based technology based on digital image correlation (DIC) for monitoring the cutting process is used.DOI: http://dx.doi.org/10.5755/j01.mech.22.5.13459

Simulation of self-compacting concrete flow in the J-ring test using smoothed particle hydrodynamics (SPH)

A range of SCC mixes with 28-day cube compressive strength between 30 and 80MPa has been prepared in the laboratory, and the time t500J (the time when the mix spread reaches 500mm) and diameter of the flow spread of each mix were recorded in the J-ring test. The entire test was then simulated from the moment the cone was lifted until the mix stopped flowing. An incompressible mesh-less smoothed particle hydrodynamics (SPH) methodology has been implemented in this simulation and a suitable Bingham-type constitutive model has been coupled with the Lagrangian momentum and continuity equations to simulate the flow. The aim of this numerical simulation was to investigate the capabilities of the SPH methodology to predict the flow of SCC mixes through gaps in reinforcing bars. To confirm that the mix flows homogeneously, the distribution of large coarse aggregates in the mixes has been simulated and examined along several cut sections of the flow pancake. It is revealed that all the simulated mixes meet the passing ability criterion with no blockage as in the laboratory J-ring test with respect to t500J, the flow spread, and aggregate homogeneity.

Corrected SPH methods for solving shallow-water equations

The artificial viscosity in the traditional smoothed particle hydrodynamics (SPH) methodology concerns some empirical coefficients, which limits the capability of the SPH methodology. To overcome this disadvantage and further improve the accuracy of shock capturing, this paper introduces two other ways for numerical viscosity, which are the Lax-Friedrichs flux and the two-shock Riemann solver with MUSCL reconstruction to provide stability. Six SPH methods with different kinds of numerical viscosity are tested against the analytical solution for a 1-D dam break with a wet bed. The comparison shows that the Lax-Friedrichs flux with MUSCL reconstruction can capture the shock wave more accurate than other five methods. The Lax-Friedrichs flux and the artificial viscosity with MUSCL reconstruction are finally both applied to a 2-D dam-break test case in a L-shaped channel and the numerical results are compared with experimental data. It is concluded that this corrected SPH method can be used to solve shallow-water equations well.

An incompressible SPH scheme with improved pressure predictions for free-surface generalised Newtonian flows

Non-Newtonian flows are of great scientific interest due to their distinctive rheological behaviour. Free-surface non-Newtonian flows are encountered in many environmental and industrial applications, such as mud flows and moulding flows. Smoothed particle hydrodynamics (SPH) is an excellent technique for describing free-surface flows, but traditionally suffers from an inaccurate pressure field. The diffusion-based incompressible SPH (ISPH) method which was first introduced by Lind et al. (2012), following the original shifting methodology of Xu et al. (2009), combines the benefits of the SPH methodology with a virtually noise-free pressure field. In this work the diffusion-based ISPH method is extended to solve inelastic non-Newtonian flows, introducing standard viscosity calculation techniques for the non-Newtonian fluids and adopting a new viscous term which is more suitable for the calculation of such flows. The new approach is validated against internal flows and free-surface flows by comparing with analytical and experimental results respectively. Furthermore, comparisons with other computational techniques were conducted and showed that in addition to the accurate prediction of free-surface flows, the proposed methodology can significantly improve the prediction of the pressure field.

Deformation of Soft Tissue and Force Feedback Using the Smoothed Particle Hydrodynamics.

We study the deformation and haptic feedback of soft tissue in virtual surgery based on a liver model by using a force feedback device named PHANTOM OMNI developed by SensAble Company in USA. Although a significant amount of research efforts have been dedicated to simulating the behaviors of soft tissue and implementing force feedback, it is still a challenging problem. This paper introduces a kind of meshfree method for deformation simulation of soft tissue and force computation based on viscoelastic mechanical model and smoothed particle hydrodynamics (SPH). Firstly, viscoelastic model can present the mechanical characteristics of soft tissue which greatly promotes the realism. Secondly, SPH has features of meshless technique and self-adaption, which supply higher precision than methods based on meshes for force feedback computation. Finally, a SPH method based on dynamic interaction area is proposed to improve the real time performance of simulation. The results reveal that SPH methodology is suitable for simulating soft tissue deformation and force feedback calculation, and SPH based on dynamic local interaction area has a higher computational efficiency significantly compared with usual SPH. Our algorithm has a bright prospect in the area of virtual surgery.

Numerical Methods and Applications in Biomechanical Modeling

Numerical Methods and Applications in Biomechanical Modeling

Numerical implementation of deformation and motion of droplet at the interface between vapor and solid surface with smoothed particle hydrodynamics methodology

In order to simulate the deformation and motion of droplet at the interface between vapor and solid surface, the smoothed particle hydrodynamics method with continuum surface force model for surface tension is modified in this paper. A surface tension algorithm with boundary conditions of wall adhesion is derived using a new treatment of boundary conditions and a corrective algorithm of particle interface normal. The colours of virtual solid particles are set according to the position of fluid surface to assure that the interface normal of particles at the junction of vapor, fluid and solid phase is normal to the contact line. By introducing Brackbill's treatment of boundary conditions of wall adhesion, the interface normal between fluid particles and some virtual solid particles at the junction of vapor, fluid and solid phase is corrected. However the module of the interface normal is kept constant. Finally, based on the new algorithm, the changing process of fluid surface in a tank, wetting process of a droplet and distortion process of a droplet on solid surface driven by shear flow are simulated. The results are compared with those obtained by volume of fluid method, showing that the new method has higher accuracy and better stability, and it is adapted to deal with the engineering problems such as the deformation and motion of droplets at the interface between vapor and solid surface.