Smoothed Particle Hydrodynamics Method Research Articles

A comparative study on waveform prediction between SPH and S-ALE methods in impact welding

To explore the optimal method for simulating impact welding, we compared detailedly the smoothed particle hydrodynamics (SPH) and structured arbitrary Lagrangian-Eulerian (S-ALE) methods in predicting bonding interface. Based on the experimental results of Cu-Q235 steel atmospheric explosive welding, an in-depth analysis was presented. The results show that the SPH and S-ALE methods converged at element sizes of 2.5 and 2 μm, respectively. When the element size was further reduced to 0.5 % of the wavelength, the errors of both methods were less than 5 %. Benefiting from the gradient mesh, the efficiency of the S-ALE method was 2–4 times that of the SPH method at the same element size. With the addition of the gas medium, the S-ALE method derived the formation mechanism of the gap gas shockwave and indicated that the pressure distribution is not uniform. Furthermore, the local high pressure of the gas shockwave prevents the vortex closure during the wave formation, generating the pore. The calculated pressure and velocity of the wavefront were 20 MPa and 3500 m s−1, respectively. In conclusion, the SPH is suitable for fast previewing waveform interfaces, while the S-ALE method has the advantage of capturing fine waveform structures under various environmental conditions.

Improvement in the Accuracy and Efficiency of Smoothed Particle Hydrodynamics: Point Generation and Adaptive Particle Refinement/Coarsening Algorithms

An adaptive particle refinement (APR) algorithm has been developed for the smoothed particle hydrodynamics (SPH) method to augment the resolution of the region of interest to achieve high accuracy and simultaneously reduce the cost of computational resources. It is widely applied in the field of fluid-controlling problems involving large interface deformations, such as the two-phase flow and fluid–structure interaction because this algorithm can capture the interface with high accuracy. Nonetheless, existing APR algorithms widely encounter computational dispersion issues at the interface of regions of different particle resolutions. Moreover, traditional shifting algorithms applied in the APR processes also have difficulties in dealing with particles with different smooth lengths. In this work, an algorithm for fast particle generation was first developed based on the accelerated ray method, which accelerates the discretization of the flow field into particles. Then, a dynamic refinement/coarsening algorithm based on the APR algorithm is proposed to solve the computational dispersion problem that occurs at the refinement/coarsening interfaces. In addition, the shifting algorithm was improved in this work to ensure the particles are always well distributed during numerical calculations and, thus, can efficiently facilitate the adaptive particle refinement/coarsening processes. Comparative analysis indicates that the robust algorithms developed for the SPH method in this work can lead to more precise and reasonable flow fields compared with the conventional SPH adaptive methods.

An improved algorithm for Finite Particle Method considering Lagrange-type remainder

The Finite Particle Method (FPM) is a significant improvement to the traditional Smoothed Particle Hydrodynamics method (SPH), which can greatly improve the computational accuracy of the entire computational domain. However, unstable calculation results and long computational time are still major obstacles to the development of FPM. Based on matrix decomposition, the fundamental equations of the traditional Finite Particle Method are rewritten and a Generalized Finite Particle Method (GFPM) is derived by introducing Lagrange-type remainder. By deriving and rewriting the fundamental equations, the GFPM method can be theoretically proven to be always stable. Numerical examples show that the GFPM method can utilize a smaller computational scale to achieve the same computational accuracy as the FPM method, with a corresponding reduction in computational time. Finally, the GFPM method is applied to a one-dimensional stress wave propagation problem and a one-dimensional heat conduction problem, and the computational results are compared with those of the SPH method and the FPM method, which verify that the GFPM has higher computational accuracy and stability.

Numerical simulation of freak wave generation and evolution process based on SPH method

With the occurrence of maritime accidents all over the world, the study of extreme waves has been promoted. These extreme waves are often called freak waves in the scientific community. At present, a variety of mechanisms are proposed to explain freak waves in the marine environment, such as directional focusing, dispersive focusing, and nonlinear modulation instability. At first, a hydrodynamic model is established based on the Smoothed Particle Hydrodynamics (SPH) method in the C# environment, and the regular wave generated by the piston wave generator is numerically simulated. Secondly, the simulation results were analyzed and visualized by using Paraview software, compared with physical experimental datas to verify the reliability of this model. Then, the generation and evolution of freak waves were numerically simulated through the movement of piston wave generators on both sides of a 2D numerical wave flume, and the influence of frequency and amplitude was analyzed by using directional focusing. The results show that if the frequency is smaller and the amplitude is larger, it is more likely to generate freak waves and wave-breaking phenomena. This study lays a foundation for the research of freak waves in the future.

Numerical Simulation on In-Vessel Molten Corium Behavior with External Vessel Cooling using Smoothed Particle Hydrodynamics

The in-vessel retention through external reactor vessel cooling (IVR-ERVC) strategy is a key management strategy for early termination of a nuclear severe accident that can threaten the integrity of the reactor vessel. To simulate the physical phenomena of the molten corium, the smoothed particle hydrodynamic (SPH) method is utilized in this study. The SPH method is a Lagrangian computational fluid dynamic (CFD) method that can simulate multi-fluid stratification, turbulence, natural circulation, radiative heat transfer, thermal ablation, and crust formation. To address the external vessel cooling, it is coupled with a conventional 1-D nuclear system analysis method. The 1-D system analysis code can calculate the two-phase natural circulation of cooling water and the convective heat transfer on the external reactor vessel wall. These two simulation codes exchange the temperature and heat flux of the reactor vessel outer wall. This study numerically simulated the IVR-ERVC strategy for a Korean high-power reactor and compared it with the traditional lumped parameter method (LPM). Unlike LPM, this study provides localized detailed data about the thermal hydraulic behavior of molten corium and visualization of phenomena in the IVR-ERVC strategy. This enhances our understanding of the phenomena in IVR-ERVC strategy and introduces new perspectives.

A gas-mechanical-damage coupling model based on the TLF-SPH method and its application to gas seepage in fractured coal

The coupled calculation of gas seepage in fractured coal is a challenge in computational mechanics. In this paper, a gas seepage model of fractured coal is developed based on smoothed particle hydrodynamics (SPH). Then, the accuracy of the seepage model based on the partial differential equation (PDE) with a constant coefficient is verified by a reference example. Moreover, the seepage characteristics of gas in homogeneous coal based on a PDE with constant and variable coefficients are analyzed, and their numerical errors are compared. Then, based on the gas seepage model of fractured coal, the effects of heterogeneity, defect opening and inclination on gas seepage in coal are studied. In addition, considering the influence of coal deformation and preexisting defects on gas seepage, a gas-mechanical-damage coupling model for gas seepage simulation is proposed by using the SPH method with the total Lagrangian formula (TLF-SPH). Subsequently, the permeability evolution and gas seepage characteristics of borehole surrounding rock under different conditions (such as overburden load, extraction pressure, borehole radius and initial gas pressure) are investigated, revealing the seepage-mechanical coupling mechanism of fractured coal during gas extraction. This work provides important theoretical support for mine gas extraction and gas outburst disaster prevention technology.

Uncertainty Analysis of Post-Failure Behavior in Landslides Based on SPH Method and Generalized Geotechnical Random Field Theory

In slope stability analysis, the inherent heterogeneity and spatial variability of soil significantly influence the aftermath of landslides, including critical aspects like runout distance, influence distance, and volume. This research integrates Smoothed Particle Hydrodynamics (SPH) with random field theory to precisely model the large deformation events in slopes with anisotropic shear parameters, while leveraging Graphics Processing Unit (GPU) parallel computing to expedite the generation of random field samples and SPH simulations. This approach meticulously examines how spatial heterogeneity of soil affects slope instability, simulating soil parameters across varied geological settings. It considers the fluctuation scale of anisotropy, the cross-correlation of cohesion and the angle of internal friction, along with their coefficient of variation (CV), to elucidate their impact on landslide magnitude and severity. This study furnishes a robust tool for a holistic assessment of slope impacts and landslide volumes. Additionally, by delineating the computational efficiency disparities between GPUs and Central processing units (CPUs), it underscores the pronounced efficiency benefits of GPU computing. The insights garnered offer fresh perspectives and methodologies in slope stability analysis and disaster risk evaluation, contributing to the finer prediction and management of this prevalent and grave geological hazard.

Coarse-grained simulation of thermal conductivity of boron nitride/epoxy composites based on DPD and SPH method

In this study, thermal conductivity (TC) of BN/polymer composites is investigated utilizing dissipative particle dynamics (DPD) and smoothed-particle hydrodynamics (SPH) methods by establishing the coarse-grained (CG) models of boron nitride nanotube (BNNT) and boron nitride nanosheet (BNNS). The Iterative Boltzmann inversion (IBI) approach is employed to calculate the parameters of the potential function of the hexagonal boron nitride (h-BN) coarse grain model for DPD method. Mesoscopic simulations on the TC of BNNT/EP, BNNS/EP, and BNNT/BNNS/EP composites are performed using SPH and DPD simulations to investigate the effects of nanofiller ratio, aspect ratio, size, and orientation on TC. The CG models established for the BNNT and BNNS structures are proven to be efficient in DPD and SPH simulations for predicting the TC of h-BN/polymer composites. Furthermore, it is demonstrated that the TC of BNNT/BNNS/EP composites is superior to that of BNNT/EP and BNNS/EP composites at the same filler ratio due to the synergistic effect of BNNT and BNNS.

Different scenarios in sloshing flows near the critical filling depth

In the present paper, the sloshing flow in a cuboid tank forced to oscillate horizontally is investigated with both experimental and numerical approaches. The filling depth chosen is $h/L=0.35$ (with h the water depth and L the tank height), which is close to the critical depth. According to Tadjbakhsh & Keller (J. Fluid Mech., vol. 8, issue 3, 1960, pp. 442–451), as the depth passes through this critical value the response of the resonant sloshing dynamics changes from ‘hard spring’ to ‘soft spring’. The experimental tank has a thickness of $0.1L$ , reducing three-dimensional effects. High-resolution digital camera and capacitance wave probes are used for time recording of the surface elevation. By varying the oscillation period and the amplitude of the motion imposed on the tank, different scenarios are identified in terms of free-surface evolution. Periodic and quasi-periodic regimes are found in most of the frequencies analysed but, among these, sub-harmonic regimes are also identified. Chaotic energetic regimes are found with motions of greater amplitude. Typical tools of dynamical systems, such as Fourier spectra and phase maps, are used for the regime identification, while the Hilbert–Huang transform is used for further insight into doubling-frequency and tripling-period bifurcations. For the numerical investigation, an advanced and well-established smoothed particle hydrodynamics method is used to aid the understanding of the physical phenomena involved and to extend the range of frequencies investigated experimentally.

A novel smoothed particle hydrodynamics method for multi-physics simulation of laser powder bed fusion

A novel smoothed particle hydrodynamics method for multi-physics simulation of laser powder bed fusion

An Innovative Coupled Common-Node Discrete Element Method-Smoothed Particle Hydrodynamics Model Developed with LS-DYNA and Its Applications

An Innovative Coupled Common-Node Discrete Element Method-Smoothed Particle Hydrodynamics Model Developed with LS-DYNA and Its Applications

Numerical simulations of thermal capillary migration of a droplet on a temperature gradient wall with smoothed particle hydrodynamics method

Thermal capillary migration is a phenomenon due to the Marangoni effect, which refers to the spontaneous motion of a liquid on a non-isothermal surface. Numerical simulation of thermal capillary migration of a droplet is extremely difficult due to the multi-physics field coupling and the violent motion of the droplet surface. In this paper, an improved smooth particle hydrodynamics (SPH) method is developed for simulating thermal capillary migration of a droplet driven by thermal gradient. In improved SPH model, an improved continuous surface force model is proposed to enhance the accuracy and stability of surface tension force calculation by introducing an improved surface tangential force. The contact angle model is utilized to model the surface wettability. The SPH method for simulating the thermal fluid flow is developed based on the continuum, momentum, and energy equations. In addition, kernel gradient correction and particle shifting technique are utilized to improve the accuracy and stability of the SPH method. The correctness and effectiveness of the improved SPH method are verified by numerical examples. Moreover, the motions of a droplet driven by thermal gradient under different conditions are investigated. Comparing with the results obtained by experiments and other resources, we can conclude that the improved SPH model is effective in modeling the thermal capillary migration of a droplet.

Wave run-up characteristic on armour layer breakwater using the smoothed particle hydrodynamics (SPH) method

Coastal structures, such as breakwater, play a critical role in protecting shorelines from the erosive forces of waves and currents. Understanding the wave run-up phenomenon on these structures is essential for designing effective coastal defense systems. This research aims to investigate the wave run-up characteristics on an armour layer breakwater using the Smoothed Particle Hydrodynamics (SPH) method (Meshless particle method based on the Lagrangian formulation), a numerical method that captures complex fluid-structure interactions. The SPH method’s inherent ability to handle free-surface flows and dynamic interactions makes it particularly suited for simulating wave run-up. The research employs numerical testing and modelling of a non-overtopping breakwater using the smoothed particle hydrodynamics method simulated with the DualSPHysics program. The wave characteristic data used in this research are the waves on the south coast of Java. The results of this research indicate that the correlation between wave run-up characteristics (Ru/H) and the Iribarren number, both using the numerical SPH method and theory, tends to exhibit a similar pattern. Remarkably, the results from both approaches exhibit a striking similarity, revealing that as the Iribarren number increases, the incremental growth of Ru/H diminishes, eventually stabilizing at a critical threshold. The Coefficient of Determination (R2) between wave run-up characteristics (Ru/H) obtained from numerical simulations using the SPH method and Günbak’s theory is 0.8824.

Numerical simulation and experimental study on seafloor sampling of an anchor-type mud collector based on SPH-FEM coupling method

Marine sediments are important for research in scientific fields such as marine geology, environmental testing of waters, marine biology and seabed resource exploration. Among them, mud miner is an important way to obtain sediments. However, due to the complexity of the marine environment, the seabed sampling operation is a relatively difficult and complicated project. The structural design of the sampler, the operation mode, and the interaction between the sampler and the sediment affect the sampling effect, which leads to the low efficiency of the sampler operation. In order to investigate the main factors affecting the drag force of the sampler during seafloor sampling, this paper takes a simple and portable anchor-type mud collector surface sediment sampler as a study. This paper introduces the mechanical structure and working principle of an anchor-type mud collector, establishes a mechanical model of the mud collector seafloor sampling process and derives the main factors affecting the dragging force: internal friction angle; the horizontal angle of the bi-directional shaft rod; undercut angle [Formula: see text] of bottom cover and dragging speed. A FEM-SPH method based on the coupling of the finite element method (FEM) and the smooth particle hydrodynamics method (SPH) was proposed to simulate the dynamic process of mud collector subsea sampling, and the mechanical data of fine sand and clay were obtained through land-based experiments. Based on the comparison between experimental data and numerical simulation data, the simulation validity of the FEM-SPH method was verified. The results show that the drag force of the clay was greater than that of the fine sand in the experiment of cutting the lower cover of the mud collector into the fine sand and clay, the internal friction angle of the clay is greater than that of the fine sand; with the increase in horizontal inclination angle and the decrease in undercut angle, the dragging force gradually increased; The dragging speed ranged from 0.2 to 0.6 m/s, with an increase in the mass of clay and fine sand collected with increasing speed, resulting in a gradual increase in dragging force. This paper provides a new method to study the force of the mud collector, provides a theoretical method to reduce the intensity and difficulty of manual work in the sampling process and increase the efficiency of sampling.

Modelling of flow characteristics in the access channel of Bali tourism port using DualSPHysics

The access channel is a structure formed as a basin on the seabed. Based on previous studies, excessive sediment accumulation in shipping lanes or access channels carried by ocean floor currents is one of the factors that cause damage to the hull under the ship. Therefore, this study aims to investigate the characteristics of seabed currents that cross the access channel. This research was carried out by modelling the numerical test of the access channel model using the Smoothed Particle Hydrodynamics (SPH) method with DualSPHysics software. The results of this study show the movement and characteristics of seabed currents that occur in the access channel at the Bali Sanur Harbor. This study obtained the average speed of seabed currents, with variations in the speed of ocean currents and forecasts regarding sediment dredging maintenance on cruise lines.

SPRAY: A smoothed particle radiation hydrodynamics code for modeling high intensity laser-plasma interactions

Here we report the development of SPRAY, a massively parallel GPU accelerated, smoothed particle hydrodynamics (SPH)-based, radiation hydrodynamics (RHD) code designed specifically for simulating high intensity laser-plasma interactions. When a target is irradiated by an intense laser, highly complex fluid deformation occurs due to instabilities, which is challenging to study numerically. SPRAY is particle-based, mesh-free, and Lagrangian, which addresses numerical issues that posed difficulties to existing methods. Its SPH formulations for RHD governing equations are tailored toward accurate and reliable simulations of laser-target irradiation phenomena, and are solved via a time-dependent, flux-limited diffusion method. A new laser energy coupling module, which is based on the Wentzel-Kramers-Brillouin (WKB) approximation, is implemented with a totally mesh-free ray-tracing scheme that is applicable for arbitrary geometry and dimensions. The accuracy and reliability of the code are demonstrated with a series of benchmark problems. To the authors' knowledge, this is the first attempt to employ SPH method for simulations of laser-plasma interactions in high energy density physics research. Possible expansions to the code, such as laser beam-beam interaction modeling and more sophisticated multi-group radiation transport are left for future development.

Coupled finite-volume method and smoothed-particle hydrodynamics method for numerical simulation of interactions between inviscid shock waves and structures

In this work, a novel coupled finite-volume method (FVM) and a smoothed-particle-hydrodynamics (SPH) method were developed for the simulation of interactions between inviscid shock waves and structures. In this approach, which considers the particles of a meshless method immersed in an FVM grid, the FVM grid cells are classified into either pure or mixed FVM cells, the latter of which contain SPH particles. A finite-element-method shape function is applied to map the variables from the SPH particles to the FVM cells, and the nodal and cell velocities are then obtained. The interaction of the fluid with the structure is computed using moving reflection boundary conditions at cell interfaces with SPH particles. The interactions of the structure with the fluid are computed from the pressure differences around the SPH particles. The processes for computing the coupled FVM–SPH method are described in detail herein. The validity of the presented coupled FVM–SPH method was verified using a theoretical model of a piston, and the numerical results were found to agree well with the theoretical approximations, indicating the accuracy of the proposed coupled method. The results of the method were then compared with the results of an experiment involving a blast-driven steel plate. Good agreement between the experimental and numerical results was obtained, and the maximum difference was 3.44%, demonstrating the effectiveness of the proposed coupled FVM–SPH method when applied to the interaction of a shock wave with a structure.

Numerical simulation and experimental study of fluid–structure interactions in elastic structures based on the SPH method

The study of fluid–structure interactions in elastic structures is highly important in hydraulic structural engineering. This paper adopts the smooth particle hydrodynamics (SPH) coupling method to simulate dam failure water impact elastic plate flow and solid coupling problems. In addition, a numerical simulation is performed on the study of the free surface flow impact of the elastic plate structure on the main dynamic characteristics, including the impact force distribution and the change process. Additionally, the elastic structure of the vibration amplitude and frequency change rule, as well as the drastic changes in free surface flow, are also carried out. In this paper, the synchronous finite element algorithm is used to analyze the problem to obtain FEM results Additionally, two-dimensional benchmark physical tests are designed for dam-break water flow impacting an elastic plate are conducted, focusing on a comparative analysis of the numerical results of the SPH method with the results of physical tests and verifying the validity, accuracy, and superiority of the SPH coupling method for solving the problem of fluid‒solid coupling in elastic structures. On this basis, to explore the relevant physical quantities that cannot be measured or described during the test process, the flow–solid coupling characteristics of the elastic plate impacted by water flow are further understood by analyzing the nature of the flow field, the change in the flow–solid force of the elastic plate and the change rule of the frequency spectrum. The results show the following: (i) The jumps in velocity between the streams and the strong curvature of the free liquid surface lead to the creation of vortices at the cavities. (ii) The flow solid force under the impact of water flow increases and then decreases, and the smaller the deformation of the elastic structure is, the greater the force is. (iii) The vibration frequency of the fixed end of the elastic structure gradually decreases along the free end frequency, and the larger the deformation of the free end of the elastic plate is, the weaker its vibration response is. In addition, the natural frequency of the elastic plate under water flow impact is slightly lower than that under free vibration of the elastic plate. The related research results provide reference and guidance for the fluid–structure interaction problem.

Dynamic simulation and failure analysis of intermittently jointed rock cells and slopes based on a novel spring-based smoothed particle hydrodynamics method

Dynamic simulation and failure analysis of intermittently jointed rock cells and slopes based on a novel spring-based smoothed particle hydrodynamics method

Numerical simulation of wedges slamming non-Newtonian fluids based on SPH method

Current research on non-Newtonian fluids using Smoothed Particle Hydrodynamics (SPH) has primarily focused on dynamic behavior, with limited exploration into interactions between rigid bodies and non-Newtonian fluids. Leveraging the SPH method's effectiveness in addressing free surface flow challenges, a two-dimensional numerical model of a rigid body impacting non-Newtonian fluids based on the Herschel-Bulkley-Papanastasiou (HBP) constitutive model is developed within the SPH framework. The study integrates experimental and numerical findings from non-Newtonian dam break scenarios, comparing particle distribution and the evolution of the waterfront over time to ensure accurate representation of non-Newtonian fluid behavior. While ensuring the convergence of SPH results, the research simulates the impact of a wedge on the surface of non-Newtonian fluids. This comparison of the slamming load exerted by non-Newtonian fluids on the wedge serves to validate the accuracy of the numerical method. Furthermore, the study explores the effects of varying initial velocities and roll angles of wedges slamming into specific non-Newtonian fluids. It analyzes fluid jet phenomena and changes in slamming loads.