Meshless Smoothed Particle Hydrodynamics Research Articles

Study on Water Entry of a 3D Torpedo Based on the Improved Smoothed Particle Hydrodynamics Method

The water entry of a torpedo is a complex nonlinear problem, involving transient impact, free surface deformation, droplet splashing, and fluid–structure coupling, which poses severe challenges to traditional mesh methods. The meshless smoothed particle hydrodynamics (SPH) method shows unique advantages in capturing the complex features of the water entry of the torpedo at different entry angles. However, it still suffers from some inherent shortcomings, such as low surface discretization accuracy, poor discretization flexibility, and low calculation efficiency. In this study, an improved adaptive SPH algorithm is proposed to investigate the water entry of the torpedo accurately and efficiently. This method integrates meshless point generation and adaptive techniques simultaneously. The numerical results demonstrate that when the torpedo vertically enters the water at different velocities, the induced impact loads acting on the head of the torpedo fluctuate significantly with two peak values in the initial stage and thereafter stabilize in a later stage. The impact load acting on the torpedo, the entry depth of the torpedo, the splash height of the droplets, and the size of the cavity generated around the torpedo increase with the increment in the entry velocity. When the torpedo enters the water at different entry angles under the same initial entry velocity, both the vertical and the horizontal movements of the torpedo are observed, which results in more complex variations in parameters along the x- and y-axes. The findings and the corresponding numerical method in this study can provide a certain basis for the future designs of the entry trajectory and the structural bearing capacity of torpedoes.

Smoothed Particle Hydrodynamics Approach for Simulation of Non-Newtonian Flow of Feedstocks Used in Powder Injection Molding

The present work aims to explore the ability to simulate flow patterns and the velocity field in the powder injection molding (PIM) process using the smoothed particle hydrodynamics (SPH) method. Numerical simulations were performed using the DualSPHysics platform. A feedstock formulated from 17-4 PH stainless steel powder (60 vol. % of powder) and a wax-based binder system was prepared to experimentally obtain its rheological properties that were implemented in DualSPHysics using two different viscosity models. The numerical simulations were calibrated, and then validated with real-scale injections using a laboratory injection press. During the calibration step, the feedstock flow momentum equation in the DualSPHysics code was modified and boundary friction coefficients at different injection rates were adjusted to create a frictional effect. During the validation step, these calibrated conditions were used to simulate the flow behavior into a more complex shape, which was compared with experimental measurements. Using an appropriate boundary friction factor, both the frictional effect of the boundaries and the stability of the numerical solution were taken into account to successfully demonstrate the ability of this meshless SPH method. The flow front length and feedstock velocity obtained in a complex cavity were satisfactorily predicted with relative differences of less than 15%.

NUMERICAL SIMULATION OF WAVE-INDUCED VEGETATION DYNAMICS USING A PARTITIONED COUPLING BETWEEN THE SPH METHOD AND AN FEA STRUCTURAL SOLVER

Sustainable coastal defense is promoted by wave-vegetation interaction that occurs in coastal zones and is able to dissipate wave energy and baffle currents. To study the complex fluid-structure interactions involved, numerical models present themselves as a suitable tool able to offer an in-depth view over the near field kinematics and dynamics. Taking into account the effect of vegetation dynamics is necessary, and often modelled through coupled fluid and structural solvers. This implies increased complexity, adaptive re-meshing tools, and numerically expensive simulations given the disparity between dimensions of the fluid domain and the very thin structural elements. The aim of this work is to present a novel numerical coupling tool based on the meshless Smoothed Particle Hydrodynamics (SPH) method, which can handle ultra-thin vegetation and resolve the vegetation kinematics without the use of any fitted parameters.

Comparative analysis of numerical solutions of 2D unsteady dambreak waves using FVM and SPH method

Abstract This work presents a comparison of two-dimensional numerical solutions of unsteady free surface flow. This is a simulation of the dam-break wave with different configurations using based-mesh finite volume method and meshless smoothed particle hydrodynamics (SPH). Two well-known approaches, widely used in the computational fluid dynamics (CFD). These techniques have proven their robustness in the numerical treatment of such conservation laws. The main goal is to check the ability of the SPH method and the first order finite volume HLLC solver to reproduce the numerical solutions of the 2D shallow water equations. Based on many benchmark tests, one investigates the effect of the topographic variation along the x and y directions on behavior of the numerical solutions namely at the wet-dry front. The comparison between the simulated results, the analytical solutions and the experimental measurements shows a good correlation, although the finite volume approach remains more advantageous in terms of accuracy and the CPU time.

Study and application of pollutant diffusion based on SPH method

In this paper, the meshless smooth particle hydrodynamics (SPH) method is used to simulate the transport process of pollutants in the environment by solving the convection-diffusion equation of pollutants under the Lagrangian framework. This method avoids various numerical problems caused by mesh distortion or mesh movement and the calculation of the derivative of the kernel function when approximating the second derivative kernel. In order to reduce the original virtual particle method of SPH to solve the boundary problem due to the large amount of particle searches will increase the amount of redundant calculation and other factors, selected with the finite difference method to solve the boundary. To verify the proposed Lagrangian particle model, numerical experiments were carried out. The one-dimensional calculation results are compared in detail with the results of different schemes in the finite difference method, and the L2, L∞ and relative errors are analyzed. The simulation results show that the SPH-based model requires fewer particles. In addition, the model is numerically analyzed under the condition of ensuring accuracy. The numerical solution is in good agreement with the analytical solution. The research results of this paper can provide a new solution and idea for environmental pollution early warning.

Mesh-free simulation of height and energy transfer of landslide-induced tsunami waves

The landslide-induced tsunami wave poses a threat to human society and the living environment by causing disasters such as run-up of water surfaces and overtopping of dams. In this paper, we systematically investigated the relationship between landslide properties and induced tsunami wave characteristics as well as the energy transfer between the landslide and waves. A meshless smoothed particle hydrodynamics (SPH) framework was presented and validated with four experiments of different landslide types. The validations indicate that the SPH model is capable of reproducing the complex processes of tsunami wave generation induced by both rigid and deformable landslides. Then we perform numerical simulations of 162 landslide-induced waves scenarios with varying landslide deformability, relative initial positions, densities, landslide size, and downstream water depths using the validated SPH model. The results show that the effect of density and initial water depth on the maximum wave height can be disregarded, while the effective landslide volume has a significant effect. The analysis of the kinetic and potential energy of the induced waves reveals that energy transfer occurs rapidly, which mainly increases the potential energy of the water downstream. We also find an exponential relationship between landslide potential energy reduction and maximum wave height. These findings provide valuable insights into the landslide-induced tsunami waves and enhance risk assessment and mitigation efforts.

SPH modeling of biomass granular flow: Theoretical implementation and experimental validation

The commercialization of biomass-derived energy is impeded by flowability challenges arising from the feeding and handling of granular biomass materials in full-scale biorefineries. To overcome these obstacles, a robust and accurate model to simulate the flow of granular biomass is indispensable. However, conventional mesh-based numerical codes are limited by inherent mesh distortion in simulating large deformation that commonly occurs in granular biomass handling. In this study, we propose a graphics processing unit (GPU)-accelerated meshless Smoothed Particle Hydrodynamics (SPH) code to model the flow of granular biomass materials. A modified void ratio-based mass conversation, a hybrid particle-to-particle/surface frictional boundary treatment, and a hypoplastic constitutive model are implemented. Four numerical examples, an elastic block sliding on inclined planes, sand column collapse, Angle of Repose, and axial compression tests for pine chips, were simulated using the developed SPH code. The results demonstrate good agreement between numerical predictions and analytical and experimental data for all four examples, validating the SPH code and increasing confidence that it can be applied to simulate more complex granular biomass handling processes, such as hopper feeding or auger conveyance.

Three-Dimensional Numerical Modeling of Lava Dynamics Using the Smoothed Particle Hydrodynamics Method

Lava domes and lava flows are major manifestations of effusive volcanic eruptions. Less viscous lava tends to flow long distances, depending on the volcanic slope topography, the eruption rate, and the viscosity of the erupted magma. When magma is highly viscous, its eruption to the surface leads to the formation of lava domes and their growth. The meshless smoothed particle hydrodynamics (SPH) method is used in this paper to simulate lava dynamics. We describe the SPH method and present a numerical algorithm to compute lava dynamics models. The numerical method is verified by solving a model of cylindrical dam-break fluid flow, and the modelled results are compared to the analytical solution of the axisymmetric thin-layer viscous current problem. The SPH method is applied to study three models of lava advancement along the volcanic slope, when the lava viscosity is constant, depends on time and on the volume fraction of crystals in the lava. Simulation results show characteristic features of lava flows, such as lava channel and tube formation, and lava domes, such as the formation of a highly viscous carapace versus a less viscous dome core. Finally, the simulation results and their dependence on a particle size in the SPH method are discussed.

Thermo-Mechanical Modelling of Friction Stir Processing of AZ91 Alloy: Using Smoothed-Particle Hydrodynamics

A thermo-mechanical model of friction stir processing (FSP) using the Altair based on meshless Smoothed-Particle Hydrodynamics (SPH) was developed and verified experimentally. Process parameters adopted for both experimentation and simulation during the FSP of AZ91 were 1000 rpm tool stirring speed, 40 mm/min tool advancing speed, and 0° tool tilt angle. The numerical analysis predicted the temperature distribution and material movement in the three phases: plunging, dwelling, and traversing. Simulated temperatures during the traversal phase were found to be greater than experimental temperatures using the Ti32 thermal camera as the heat was only transported by friction and plastic deformation. Peak temperatures for all three phases were observed to be in the range of 47% to 87% of the material’s melting point and are in accordance with the findings of the experiments. The SPH mesh-free model was proven to be capable of predicting the in-process thermal-mechanical state variables during and after the process by extracting morphology. The material movement around the tool has been predicted using SPH node tracking, which further anticipates that there was no complete flow of SPH nodes from RS to AS, leaving a gap that must be filled. Post-processed morphology shows inadequacy in the material flow due to lower compressive force. It formed the wormhole at the advancing side’s trailing and was verified experimentally.

Smoothed particle method for fluid-structure interaction

<p indent="0mm">The full Lagrangian meshless smoothed particle hydrodynamics (SPH) method has experienced a tremendous enhancement in methodology and has played a key role in a range of scientific and industrial applications involving complex multi-physics systems. This paper presents a concise survey of the SPH method and its applications in fluid-structure interaction (FSI), including (1) theory and fundamental with kernel corrections; (2) the Riemann-SPH method and dissipation limiting scheme; (3) total Lagrangian formulation with the stabilized scheme; (4) FSI scheme with interface treatments, and multi-resolution scheme.

Fluid–structure interaction approach with smoothed particle hydrodynamics and particle–spring systems

This paper presents a novel three-dimensional fluid–structure interaction (FSI) approach, where the meshless smoothed particle hydrodynamics (SPH) method is used to simulate the motion of incompressible fluid flows, whilst structures are represented by a simplified approach based on particle–spring systems. The proposed FSI technique allows to use independent spatial–temporal resolutions for the fluid and structural computational domains. The particle–spring elastic constants are calibrated and relationships with the mechanical material properties, Young’s modulus and Poisson’s ratio, are determined. Fluid and structure computational domains are separated by interfaces made of triangular elements whose position is updated during the simulation following the structural deformation. The coupling of the two media at the fluid–structure interfaces is handled by the introduction of solid and fluid boundary particles. This approach, automatically and without introducing further complexity, avoids the penetration of fluid particles into the solid domain. The efficiency and accuracy and the present method are validated with analytical/benchmark solutions from the literature.

Experimental and Numerical Investigations of In Situ Alloying during Powder Bed Fusion of Metals Using a Laser Beam

Powder Bed Fusion of Metals using a Laser Beam (PBF-LB/M) is increasingly utilized for the fabrication of complex parts in various industrial sectors. Enabling a robust and reproducible manufacturing process is one of the main goals in view of the future success of PBF-LB/M. To meet these challenges, alloys that are specifically adapted to the process are required. This paper demonstrates the successful interplay of simulation studies with experimental data to analyze the basic phenomena of in situ alloying. The meshless Smoothed-Particle Hydrodynamics (SPH) method was employed for the numerical simulation of two-component powder systems considering both thermodynamics and fluid mechanics in the solid and the melt phase. The simulation results for the in situ alloying of stainless steel 316L blended with the aluminum alloy AlSi10Mg were enriched and validated with the data from a novel experimental test bench. The combination of both approaches can enhance the understanding of the process for in situ alloying. Therefore, future investigations of the PBF-LB/M process with multi-component powder systems can benefit from detailed numerical studies using SPH.

3-D Numerical Study of a Bottom Ramp Fish Passage Using Smoothed Particle Hydrodynamics

Worldwide, the overwhelming number of man-made barriers in fluvial systems has been identified as one of the major causes of the reported staggering average declines of migratory fish. Fish passages have been shown to help mitigate such problems. Close-to-nature types of fish passages, such as bottom ramps, bypass channels, and fish ramps can be used to minimize the impact of artificial steep drops (e.g., weirs) on the migration of aquatic fauna, especially in cases of low-head barriers. This study focuses on the characterization of the flow pattern in a bottom ramp. A 3-D numerical model based on the meshless smoothed particle hydrodynamics (SPH) method was successfully validated and then employed for the simulation of turbulent free-surface flow in a straight channel with complex geometry. The effects of bed roughness, channel slope, and flow rate were quantified in terms of flow depth, velocity fields, and area‒velocity ratios. During the study, several new tools were developed, leading to new functionalities in pre-processing, solver, and post-processing which increase the applicability of DualSPHysics in the field of eco-hydraulics.

A fluid–structure interaction model for free-surface flows and flexible structures using smoothed particle hydrodynamics on a GPU

This paper presents the development of a numerical model for violent hydrodynamics of free-surface flows interacting with flexible structures using the meshless smoothed particle hydrodynamics (SPH) method accelerated with a graphics processing unit (GPU). The present work implements a unified SPH framework to solve both the fluid and structural dynamics within the open-source SPH code DualSPHysics. Well-known deficiencies with SPH-based structural modelling (linear inconsistency, tensile instability and rank deficiency) are addressed by adopting a Total Lagrangian formulation with kernel correction and zero-energy mode suppression. The fluid–structure coupling is handled via manipulation of the existing boundary condition within DualSPHysics, which does not require any geometrical knowledge of the interface. This, together with the unified SPH framework, permits straightforward implementation within DualSPHysics and retains its parallel scalability on hardware acceleration platforms, in particular on GPUs. An extensive validation and profiling of the proposed model is carried out for a range of challenging 2-D and 3-D test cases incorporating violent free-surface flows, nonlinear structural dynamics and complex fluid–structure interactions, and its performance is characterised and quantified. The analysis shows good agreement between the proposed model and analytical/benchmark solutions from the literature. Furthermore, the GPU profiling shows speedups on a single GPU of up to 40, compared to an optimised 12-core (24 threads) central processing unit (CPU) version. These findings indicate the proposed model is a viable and efficient approach to simulating violent free-surface fluid–structure interactions.

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.

Meshless SPH analysis for transient heat conduction in the functionally graded structures

Transient heat conduction analysis of the functionally graded structures is of great importance for the structure design and manufacturing. In this study, 2D heat conduction problem is solved by the meshless smoothed particle hydrodynamics (SPH) method. To improve the computational accuracy and efficiency of traditional SPH method, a symmetric SPH approach is adopted, which can calculate a function and its derivatives of higher order using one symmetric matrix. The heat conduction function is discretized by the improved SPH method, as well as the boundary conditions. The SPH analysis of the heat conduction in several functionally graded structures with different geometries is performed and validated by the analytical values and the FEM results in literature. The effect of the graded index on the temperature distribution in the structure domain is also studied. The present paper provides an alternative potential method for the heat conduction analysis of functionally graded materials.

Simulation of weak‐inertia single‐phase flow in porous materials using Smoothed Particle Hydrodynamics

AbstractIntrinsic permeability of a porous material is a crucial material parameter in various application fields like e.g. geosciences, materials science, biological sciences and mechanical engineering. In contrast to the permeability often used in purely linear models, however, it is also a (nonlinear) function of the Reynolds number (Re) with the onset of the influence of inertial forces. In coarse‐grained continuum models the Forchheimer equation describes this incipient influence of viscous momentum exchange but it is based on the adaptation of experimentally obtained data and its range of validity remains a subject for discussion. Performing three‐dimensional Direct Numerical Simulations for single‐phase flow through porous media this work aims to show a smooth transition of effective intrinsic permeability within the interval 0.1 &lt; Re &lt; 1000. We use the fully‐Lagrangian meshless Smoothed Particle Hydrodynamics method (SPH) to solve the weakly compressible Navier‐Stokes equations for pore‐scale resolved flow in the so‐called weak‐inertia regime. Our implementation utilizes HOOMD‐blue thus allows us to perform massively parallel computations which are crucial for these applications.

On the Location of Multiple Failure Slip Surfaces in Slope Stability Problems Using the Meshless SPH Algorithm

The occurrence of multiple critical slip surfaces with equal importance in rehabilitating and reinforcing slopes has been frequently observed in geotechnical engineering practices. The simultaneous determination of these potential slip surfaces is, however, not trivial. This paper presents a methodology based on the smoothed particle hydrodynamics (SPH) approach, which can simultaneously determine multiple failure slip surfaces and the debris flow process without previous knowledge or trial-and-error processes, and this methodology is validated against a slope with the presence of multiple critical slip surfaces. The proposed methodology serves as an efficient and effective alternative approach to traditional approaches, which involve cumbersome treatments performed by engineers based on their subjective experiences. The multiple sources of failure slip surfaces in slope stability are equivalent to multiple sources of initiation of slope failure, and it is found that SPH can provide a direct and systematic tool for identifying multiple failure slip surfaces. However, some minor potential problems are also found with the use of the SPH method in actual applications.

A meshless method for topology optimization of structures under multiple load cases

This paper focuses on a new topology optimization method for the structures under multiple loading cases. Meshless Smoothed Particle Hydrodynamics (SPH) method is improved to accurately and stably solve solid mechanics. Design variable is chosen as the particle’s density, which has the same interpolation scheme as the displacement field. The smoothness of density field is improved and the [0,1] bounds of density field can be always ensured. The compliances related to each load are calculated by SPH method and are weighted to form the objective function. By using the modified Solid Isotropic Material with Penalization (SIMP) method and Optimality Criteria (OC) method, the densities and material properties of SPH particles are renewed iteratively. Three topology optimization problems are successfully solved and validated by comparing the results to the ones in literature. The mesh-dependency and checker-board phenomenons do not appear, which demonstrates the effectiveness of the proposed SPH algorithm.

An axisymmetric solid SPH solver with consistent treatment of particles close to the symmetry axis

A meshless smoothed particle hydrodynamics solid solver is developed in order to study fluid–structure interactions and to predict cavitation erosion. The solid solver is developed in-house in an axisymmetric configuration. The existing SPH methods dedicated to solid materials do not allow a consistent treatment of particles close to the symmetry axis, so a density correction scheme is proposed here to derive new density and momentum equations for solid mechanics in axisymmetric SPH formulation. The new SPH equations are coded in the solver, and the SPH solid solver is then validated against FEM results, which shows excellent agreement.