Smoothed Particle Hydrodynamics Technique Research Articles

3D SPH analysis of focused waves interacting with a floating structure

In recent years, the number of offshore floating structures has been growing and is expected to continue growing. Due to climate change, the frequency and severity of extreme waves are increasing. Numerical models can be a strategic tool in the reliable design and optimization of marine structures. However, the number of numerical parameters to be tuned plays a crucial role, as they could limit the model’s applicability and reliability. Furthermore, there are many challenges in modelling wave-structure interaction. Among these challenges, the simulation of one-dimensional tethers is of great concern when dealing with moored floating structures. In this study, a 3D numerical model is developed based on the Smoothed Particle Hydrodynamics (SPH) technique. This hydrodynamic model is coupled with a multi-body solver for the dynamic analysis of moorings and structures. In a three-dimensional numerical flume, focused ocean waves are generated with a piston-type wave-maker and propagated until impact with the floating structure. The developed model predicts the wave profile, impact forces, and structural dynamics, and is validated by comparing numerical results against experimental data.

Computational Modelling and Comparative Analysis of Friction Stir Welding and Stationary Shoulder Friction Stir Welding on AA6061

This research focuses on the computational modelling and comparative analysis of friction stir welding (FSW) and stationary shoulder friction stir welding (SSFSW) applied to AA6061-T6 aluminium alloy. SSFSW, an FSW variant, employs a stationary shoulder and a rotating pin. This study introduces a numerical model for both processes, using the innovative Smoothed Particle Hydrodynamics (SPH) technique to capture their distinct thermo-mechanical characteristics. The aim is to unravel its mechanics and multi-physics in SSFSW and compare it with conventional FSW. The temperatures predicted by the model exhibited a close agreement between the advancing side (AS) and retreating side (RS). Plastic strain patterns show that regular FSW is different from SSFSW. In SSFSW, the strain is less, and the plastic area is comparatively slightly narrower. The distinct “ironing effect” resulting from the stationary shoulder in SSFSW reduces the heat-affected zone (HAZ). Yet, it maintains efficient plasticisation and material flow within the pin-affected zone (PAZ). This research emphasises the significant impact of temperature, strain, material flow, and thermo-mechanical characteristics on the quality of joints. Future suggestions include exploring process parameters more broadly, examining dissimilar welding techniques and hybrid approaches, and comprehensively investigating the diverse effects of SSFSW under various configurations and joint angles.

Research on oil boom performance based on Smoothed Particle Hydrodynamics method.

To address the issues of fluid-solid coupling, instability in the liquid two-phase flow, poor computational efficiency, treating the free surface as a slip wall, and neglecting the movement of oil booms in simulating oil spill containment, this study adopts the Smoothed Particle Hydrodynamics (SPH) method to establish a numerical model for solid-liquid coupling and liquid two-phase flow, specifically designed for oil boom containment and control. The DualSPHysics solver is employed for numerical simulations, incorporating optimized SPH techniques and eight different skirt configurations of the oil boom into the numerical model of two-phase liquid interaction. By setting relevant parameters in the SPH code to enhance computational efficiency, the variations in centroid, undulation, and stability of undulation velocity for different oil boom shapes are observed. The experimental results demonstrate that the improved oil boom exhibits superior oil containment performance. These findings provide a theoretical basis for the design of oil boom skirt structures.

Three-Dimensional Smooth Particle Hydrodynamics Modeling and Experimental Analysis of the Ballistic Performance of Steel-Based FML Targets.

In this paper, shields made of 1.3964 stainless steel bonded to a fiber laminate were subjected to ballistic impact response of 7.62 × 51 mm ŁPS (light projectile with a lead core) projectiles. Additionally, between the steel sheet metal and the laminate, a liquid-filled bag was placed, which was a mixture of ethylene glycol (C2H6O2) with 5 wt.% SiO2 nanopowder. Numerical modeling of the projectile penetrating the samples was carried out using the finite element method in the Abaqus program. The elasto-plastic behavior of the projectile material and the component layers of the shields was taken into account. Projectile penetration through glycol-filled bag has been performed using the smooth particle hydrodynamics technique. The morphology of the penetration channel was also analyzed using a scanning electron microscope. For the shield variant with a glycol-filled bag between the steel and laminate plates, the inlet speed of projectile was 834 m/s on average, and 366 m/s behind the sample. For the variant where there was no glycol-filled bag between the steel and laminate plates, the inlet and outlet average velocities were 836 m/s, after 481 m/s, respectively. Referring to the steel-glycol-laminate and steel-laminate variants, it can be concluded that the laminate-glycol-laminate is more effective.

Realistic computer modelling of stent retriever thrombectomy: a hybrid finite-element analysis-smoothed particle hydrodynamics model.

Stent retriever thrombectomy is a pre-eminent treatment modality for large vessel ischaemic stroke. Simulation of thrombectomy could help understand stent and clot mechanics in failed cases and provide a digital testbed for the development of new, safer devices. Here, we present a novel, in silico thrombectomy method using a hybrid finite-element analysis (FEA) and smoothed particle hydrodynamics (SPH). Inspired by its biological structure and components, the blood clot was modelled with the hybrid FEA-SPH method. The Solitaire self-expanding stent was parametrically reconstructed from micro-CT imaging and was modelled as three-dimensional finite beam elements. Our simulation encompassed all steps of mechanical thrombectomy, including stent packaging, delivery and self-expansion into the clot, and clot extraction. To test the feasibility of our method, we simulated clot extraction in simple straight vessels. This was compared against in vitro thrombectomies using the same stent, vessel geometry, and clot size and composition. Comparisons with benchtop tests indicated that our model was able to accurately simulate clot deflection and penetration of stent wires into the clot, the relative movement of the clot and stent during extraction, and clot fragmentation/embolus formation. In this study, we demonstrated that coupling FEA and SPH techniques could realistically model stent retriever thrombectomy.

An improved smoothed particle hydrodynamics approach using new inverse kernel function

The main limitation of Smoothed Particle Hydrodynamics (SPH) method that resists the method's potential is its lack of providing stability and accuracy to the numerical technique. We improve the accuracy of the standard SPH technique, by formulating a new inverse logarithmic kernel function. This new kernel function is derived based on the underlying properties of kernel functions. The approximation technique used here is based on the Moving Least Squares based technique. The adequacy of the proposed kernel function is tested by simulation of 2D shock wave propagation and 3D dam-break free surface flow against a cuboidal obstacle. The method was validated against experimental data by Kleefsman et al., [1]. The numerical results reveal that our new SPH approach using inverse logarithmic kernel function outperforms existing ones in particle restoration, zero error, better accuracy and enhanced efficiency in kernel approximation. This new kernel function showed some improvement over existing kernels by showing very less error approximation value of 0.035h2. The results showed some improvements over standard technique by being capable of handling problems with large deformations accurately and precisely.

High-order consistent SPH with the pressure projection method in 2-D and 3-D

Mesh-free methods such a smoothed particle hydrodynamics (SPH) have advantages over mesh-based methods for flow in complex domains but attaining consistent high-order accurate solutions with the conventional form of SPH has yet to be resolved. The high-order smoothing error dominates the SPH error until increasingly fine resolutions cause the low-order discretisation error to dominate; this is related to discretising a volume integral into a summation. In this paper, a high-order consistency correction based on modified SPH (MSPH) and the modified finite particle method (FPM) is proposed for improving the order of the limiting discretisation error. The new technique is an arbitrarily high-order extension of these schemes where the complexity of the consistency correction and the required computations are reduced by using simplified versions of the smoothing kernel derivatives. Tested in Eulerian form, the proposed high-order consistent SPH technique (HOCSPH) is combined with new high-order SPH kernel functions, designed to improve the order of the SPH smoothing error, and the resulting hybrid technique is shown to converge according to the smoothing error initially before converging according to the HOCPSH error once the latter becomes dominant. The initial high-order convergence lowers the computational effort required to achieve higher accuracy with hybrid HOCSPH in comparison to HOCSPH with second-order smoothing accuracy kernel functions. However, for highly irregular distributions it is found that the use of kernels with second-order smoothing accuracy provides more consistent convergence properties. A number of flows are simulated in 2-D and 3-D using the new HOCSPH technique in combination with the pressure projection method, and the results show that the method is accurate and able to model highly complex flow patterns. Some issues with stability of the projection method related to pressure–velocity collocation are identified, and several remedies are proposed. While effective for the test cases herein, these remedies are new in this context and require further attention for generalisation in future studies.

Quasi-static and low-velocity impact biaxial flexural fracture of aluminosilicate glass — An experimental and numerical study

In this study, the quasi-static biaxial fracture behavior of aluminosilicate glass is investigated via Ball-On-Ring (BOR) and Ring-On-Ring (ROR) tests aided by a three-dimensional Digital Image Correlation (3D-DIC) technique. In-plane strain field and out of plane deformation distribution during the loading process can be obtained by this test system, overcoming the problem of inaccurate displacement data provided by the loading machine. During the loading process, a uniform strain distribution field is formed below the load ring of the ROR specimen while a gradient strain distribution is built for the BOR specimens. For dynamic loading conditions, low-velocity impact BOR tests are conducted at velocities of 2 m/s and 4 m/s showing a dynamic strengthening effect and high-speed cameras provide detailed fracture and failure sequences of the glass plates. Finite Element Method (FEM) simulations with the JH-2 material model are carried out showing good consistency with experimental results for the quasi-static loading conditions. FEM coupled to Smooth Particle Hydrodynamics (FEM-SPH) technique is utilized for dynamic simulations to solve the element distortion and non-physical problems. The influence of the tensile strain rate effect on low-velocity impact behavior of aluminosilicate glass is analyzed in detail. The original JH-2 model does not provide a reasonable prediction of the dynamic tensile response of brittle materials and the model requires further modifications to describe the dynamic tensile fracture behavior. By introducing rate-dependence maximum hydrostatic tensile strength σt,max to the updated model, better predictions for the contact force and projectile residual velocity histories of low-velocity impact tests can be provided.

SPH Open Boundary Simulation of Free-Surface Flow Over Ogee-crested Spillway

This study was conducted to compare water surface profiles with standard ogee-crested spillways. Different methods were used, such as (experimental models, numerical models, and design nomographs for the United States Army Corps of Engineers, USACE). In accordance with the USACE specifications, three different models were constructed from rigid foam and then installed in a testing flume. The water surface profile has been recorded for these models with different design heads. For modeling the experimental model configurations, a numerical model based on the smoothed particle hydrodynamics (SPH) technique was used and is developed to simulate the water surface profile of the flow over the ogee-crested spillway. A 2D SPHysics open-source software has been used in this study, using the SPH formulation to model fluid flow, developing the SPH boundary procedure to handle open-boundary simulations, and modifying the open-source SPHysics code for this purpose. The maximum absolute difference between the measured and computed results of the water surface profile for all head ratios of (H/Hd), does not exceed 4.63% at the crest region, the numerical results for the water surface profile showed good agreement with the physical model results. The results obtained experimentally and numerically by SPH are compared with the CFD results in order to be more reassuring from the results. Additional comparisons were made using interpolated data from USACE, Waterways Experiment Station (WES), and design nomographs. The SPH technique is considered very promising and effective for free surface flow applications.

Efficient thermomechanical analysis of functionally graded structures using the symmetric SPH method

Tailoring the thermal and mechanical properties plays an important role in manufacturing and designing functionally graded material (FGM) which is often applied in high temperature gradient environment. The present investigation will address the basics of thermoelastic problem solved by means of a specific meshless smoothed particle hydrodynamics (SPH) method. The inconsistency of the conventional SPH method was improved by introducing the symmetric SPH (SSPH) technique, where function derivatives can be approximated by the function values in the support domain. Hence, the heat conduction and balance equations become a series of algebraic equations, which can be solved efficiently. The result accuracy achieved by the proposed approach was demonstrated in solving several numerical examples in comparison to available results in the literature. The effect of the gradation indexes on the thermoelastic behavior was also considered.

Modeling and Simulation Techniques Used in High Strain Rate Projectile Impact

A series of computational models and simulations were conducted for determining the dynamic responses of a solid metal projectile impacting a target under a prescribed high strain rate loading scenario in three-dimensional space. The focus of this study was placed on two different modeling techniques within finite element analysis available in the Abaqus software suite. The first analysis technique relied heavily on more traditional Lagrangian analysis methods utilizing a fixed mesh, while still taking advantage of the finite difference integration present under the explicit analysis approach. A symmetry reduced model using the Lagrangian coordinate system was also developed for comparison in physical and computational performance. The second analysis technique relied on a mixed model that still made use of some Lagrangian modeling, but included smoothed particle hydrodynamics techniques as well, which are mesh free. The inclusion of the smoothed particle hydrodynamics was intended to address some of the known issues in Lagrangian analysis under high displacement and deformation. A comparison of the models was first performed against experimental results as a validation of the models, then the models were compared against each other based on closeness to experimentation and computational performance.

Numerical and experimental investigation on aluminum 6061-V-grooved stainless steel 304 explosive cladding

This study attempts to analyze the microstructure and interface behavior of aluminum 6061 (Al 6061)-V-grooved stainless steel (SS304) explosive cladding by numerical and experimental methods. Numerical simulation was performed by Smoothed Particle Hydrodynamics (SPH) technique, in ANSYS AUTODYN, and the results are correlated with experimental outcome. The machining of V-grooves on the base plate transform the melted layer formed in conventional cladding (without grooves on the base plate) into a smooth undulating interface, for a similar experimental condition. The flyer plate and collision velocities, observed in numerical simulation, are in good agreement to the analytical expectations. The pressure developed in the flyer plate is higher than the base plate and the maximum pressure is witnessed at the collision point irrespective of grooved base plate or otherwise. The temperature developed in the collision point of conventional explosive cladding exceeds the melting point of both the participant metals, whereas, it exceeds the melting point of aluminum alone, in case of V-grooved base plate cladding. The shear and impact strengths of the V-grooved base plate clads are higher than the conventional clads and the fracture surfaces exhibit mixed modes of fracture.

Rolling resistance prediction of off-road tire using advanced simulation and analytical techniques

This paper focuses on developing a relationship between the rolling resistance coefficient of an off-road truck tire running over different terrains and at various operating conditions. The various operating conditions include tire speed, vertical load, and inflation pressure. The different terrains include dry and moist sand, flooded surface, snow, dense sand, clayey soil, and sandy loam with moisture. The off-road truck tire size 315/80R22.5 is modeled and validated using the finite element analysis technique, while the terrains are modeled and calibrated using smoothed-particle hydrodynamics technique. Artificial neural network and genetic algorithm (GA) are then used to develop a relationship between the rolling resistance coefficient and the terrains and operating conditions. The results of both algorithms are compared to the simulation results in terms of R-square goodness of fit and the mean squared error. Finally, a numerical equation is presented that determines the rolling resistance coefficient as a function of the terrains parameters and the operating conditions. It was found that both techniques provide a suitable solution, however, the GA provides an explicit equation.

Rock Cutting Simulation of Point Attack Picks Using the Smooth Particle Hydrodynamics Technique and the Cumulative Damage Model

Various numerical methods have been used to simulate the rock cutting process. Numerical simulation is a useful tool for estimating the performance of a cutting tool and for understanding the mechanism of rock cutting and interaction between a cutting tool and the rock. These methods supplement the rock cutting test, which is commonly referred to as the linear cutting machine (LCM) test. Mechanical excavators, such as roadheaders, longwall shearers, and trenchers, generally use pick cutters as the cutting tool. In this study, a rock cutting simulation with a pick cutter was developed using the smooth particle hydrodynamics (SPH) technique, which is a mesh-free Lagrangian method. The Drucker–Prager (DP) strength model was used to simulate the brittle behavior of rock. The cumulative damage (CD) model was used to simulate the degraded fragmentation process of rock and the distinctive behavior of rock in the compression and tensile stress regions. In this study, an attempt was made to simulate sequential cutting by multiple pick cutters. The results showed that the numerical simulation matched the experimental results closely in terms of cutter forces, specific energy, and the fragmentation phenomenon. These results confirmed the applicability of the SPH technique in simulating the rock cutting process.

Modelling of debris flows and flash floods propagation: a case study from Italian Alps

Storage basins, check dams, barriers and other control works are often used to reduce threats and damage from flow-like mass movements. This paper deals with the effectiveness of two storage basins of the Italian Alps against debris flows followed by a flash flood induced by short heavy rainfall in 2009. Referring to detailed field data, the propagation of flows and their interaction with the control works are analysed by using an advanced numerical depth-averaged flow propagation model based on SPH (Smooth Particle Hydrodynamics) technique. The Froude dynamic similitude is here used to provide a quantitative descriptor of the dynamic features of the flows. The numerical results show that debris flows accumulated in the storage basins since they propagated downslope like subcritical flows. On the contrary, flash floods overpassed the control works having moved along the entire path as supercritical flows. Those findings are fully supported by some previous studies and provide a further contribution to the relevant topic of granular flow-obstacle interaction.

Self-gravitating barotropic equilibrium configurations of rotating bodies with smoothed particle hydrodynamics

Context. Self-gravitational rotating bodies do not have spherically symmetric geometries. The study of physical events appearing in fast-spinning compact stars and accretion disks, for example those due to localized thermonuclear ignitions in white dwarfs or to the role played by hydrodynamic instabilities in stars and disks, often requires 3D simulations. When the numerical simulations are carried out with the smoothed particle hydrodynamics (SPH) technique a critical point arises as to how to build a stable initial model with rotation because there is no well-established method for that purpose. Aims. We want to provide a portable, easy-to-implement methodology for SPH simulations to procedurally generate physically sound, stable initial conditions for rotating bodies. Methods. We explain and validate an easy and versatile novel relaxation method to obtain 3D equilibrium configurations of rotating bodies with SPH. As detailed below, this method is able to relax barotropic, P(ρ), structures either in rigid or differential rotation. The relaxation procedure strongly relies on the excellent conservation of angular momentum that characterizes the SPH technique. Results. We applied our proposal to obtain stable rotating structures of single white dwarfs, compact binaries harboring two white dwarfs, high-density stars approached as polytropes and accretion disks either in rigid or differential rotation. Conclusions. We present a novel relaxation method to build 3D rotating structures of barotropic bodies using the SPH technique. The method has been successfully applied to a variety of zero-temperature white dwarfs and polytropic self-gravitating structures. Our SPH results have been validated by comparing the main features (energies, central densities, and the polar-to-equatorial radius ratio) to those obtained with independent grid-based methods, for example, the self-consistent field method, showing that both methods agree within a few percent.

Smoothed particle hydrodynamics modeling of the thermal behavior of double skin facades in fires considering the effects of venetian blinds

At present, the fire safety of double skin facades (DSFs) is an important research area due to recent spikes in fires in high rise buildings involving glass DSF systems, and also due to our limited understanding of the thermal behavior of these systems. To overcome this lack of knowledge, a numerical framework is proposed for simulating the thermal performance of DSFs under fire conditions. The framework is based on the smoothed particle hydrodynamics technique and it can be used to compute numerical solutions and simulate the thermal degradation of DSFs under fire conditions. The numerical model was validated by comparing the predicted response parameters in a fire exposed DSF system with those measured in fire experiments. The validated numerical model was then employed to derive empirical equations linking temperature with both the time and location along the interior and exterior glass panes of DSFs. Finally, numerical simulations were conducted for the same DSF configuration but equipped with venetian blinds in order to examine the influence of the blinds on the fire performance of glass DSFs. An in-house MATLAB code was developed and implemented to conduct these numerical simulations. The results obtained from these numerical simulations clearly indicated that the “blind tilt angle” can significantly affect the fire spread characteristics and temperature distribution in DSFs, and thus it should be considered in the design of DSF systems for high rise buildings.

Numerical modeling of the tool-rock penetration process using FEM coupled with SPH technique

The numerical simulation of penetration into rock is an important tool to gain insights into rock drilling mechanisms, since it can be exploited as an alternative to the expensive field testing. This research aims to present an innovative computer simulation of rock penetration process on the basis of the finite element method (FEM) coupled with smoothed particle hydrodynamics (SPH). An advanced material model, namely the Karagozian and Case Concrete (KCC) model, was employed for this purpose. The Punch Penetration test (PPT) was carried out on a medium strength sandstone for validating the numerical method. The comparison of the numerical and experimental results obtained concluded that the FEM coupled with SPH method in conjunction with the fully calibrated KCC material model is a reliable method for the study of rock penetration due to its ability to deal with large deformations and its realistic constitutive modeling. The modeling approach was finally applied to estimate the required force to penetrate an offshore reservoir rock block under the in-situ confining pressure with a double conical tool up to 5 mm depth. The effective stresses in sedimentary basins of Agosta and Dosso Campus at a depth of 3000 m below the seabed are considered as the confining pressures of this study.

Prediction of energy dissipation of off-road vehicles using smoothed-particle hydrodynamics techniques

This paper studies the energy dissipated during experimental and simulated procedures for the pressure-sinkage and shear-strength test. These tests are performed using a clayey-loam soil and modelled as smoothed-particle hydrodynamics (SPH) technique in Visual Environment's Pam-Crash software. The hydrodynamic elastic plastic material is used to define the equation of state for the clayey-loam soil. The soil is modelled at five different levels of compaction to represent multi-pass of a tyre over soil. The soil calibration is performed using the pressure-sinkage and direct shear-strength test and validated using experimental data from a soil bin facility. The energy dissipation is calculated using the soil sinkage values at every pass of wheel. Finally, the results of experimental and simulation dissipation energy are discussed and the effect of the tyre multi-pass on dissipated energy is investigated and presented. This research will further continue to model an agricultural FEA tyre over the clayey-loam soil to compute tyre performance and interaction characteristics.

Prediction of energy dissipation of off-road vehicles using smoothed-particle hydrodynamics techniques

Prediction of energy dissipation of off-road vehicles using smoothed-particle hydrodynamics techniques