Nonlinear wave interaction with curved front seawalls

In this paper, a new bird model which combined the visco-elastic material properties and Smooth Particle Hydrodynamics (SPH) method has been proposed to simulate the bird features in high-speed conditions. A rigid plate impact test was adopted to compare the reaction of SPH and Lagrangian bird model. Compared with the results of Lagrangian bird model, new SPH model was more in line with the experimental data, and has better computational efficiency. The SPH bird model was further used to bird impacting with the wing leading edge by using finite element program LS-DYNA. Two kinds of leading edge structural enhancement programs have been proposed and carried out simulation of bird impact. Basis of calculation, the design parameters of experimental structure was determined and was produced to wait for final testing.

Simulation of wave overtopping by an incompressible SPH model

To improve the application of Smoothed Particle Hydrodynamics (SPH) method, a new Visual Basic-Fortran (VBF) SPH model with the improvements on efficiency and visualizable interface is presented. The VBF SPH model is based on mixed language programming (MLP) method that not only improved SPH model’s efficiency, but also created the interface functions to control and observe the whole simulation. İts general structrue is to compiling the Fortran computing subroutines into Dynamic Link Library (DLL) files and these files will be called by Visual Basic (VB) programs during the calculation. Besides that an improved link-list algorithm, is described detailedly. This algorithm improves the model’s searching efficiency by reducing the number of searching cells. Two classical problems, Flood flow over Dam and Droplet-Impact, are chosen to analyze the VBF SPH model efficiency and distinguish the improvements’ effect. Both of problems are simulated respectively by VBF SPH model and VB model. According to first simulation VBF SPH model is more than 8 times faster than the VB model. And the second simulation refers that the MLP method increased about 7 times efficiency while the improved link-list algorithm increased more than 1 time.

3D multi-resolution SPH modeling of the water entry dynamics of free-fall lifeboats

Purpose – The purpose of this paper is to present an efficient smoothed particle hydrodynamics (SPH) method particularly adapted for the geometrically nonlinear analysis of structures. Design/methodology/approach – In order to resolve the inconsistency phenomenon which systematically occurs in the standard SPH method at the domain’s boundaries of the studied structure, the classical kernel function and its spatial derivatives were modified by the use of Taylor series expansion. The well-known tensile instabilities inherent to the Eulerian SPH formulation were attenuated by the use of the Total Lagrangian Formulation (TLF). Findings – In order to demonstrate the effectiveness of the present improved SPH method, several numerical applications involving geometrically nonlinear behaviors were carried out using the explicit dynamics scheme for the time integration of the PDEs. Comparisons of the obtained results using the present SPH model with analytical reference solutions and with those obtained using ABAQUS finite element (FE) commercial software, show its good accuracy and robustness. Practical implications – An additional application including a multilayered composite structure and involving buckling and delamination was investigated using the present improved SPH model and the results are compared to the FE results, they confirmed both the efficiency and the accuracy of the proposed method. Originality/value – An efficient 2D-continuum SPH model for the geometrically nonlinear analysis of thin and thick structures is proposed. Contrarily to the classical SPH approaches, here the constitutive material relations are used to link naturally the stresses and strains. The Total Lagrangian approach is investigated to alleviate the tensile instabilities problem, allowing at the same time to avoid the updating procedure of the neighboring particles search and therefore reducing CPU usage. The proposed approach is valid for isotropic and multilayered composites structures undergoing large transformations. CPU time savings and better results with the new 2D-continuum SPH formulation compared to the classical continuum SPH. The explicit dynamic scheme was used for time integration allowing a fast resolution algorithm even for highly nonlinear problems.

SPH Modeling Improvements for Hypervelocity Impacts

Numerical simulations of water entries based on a three-dimensional parallelized Smoothed Particle Hydrodynamics (SPH) model developed by Ecole Centrale Nantes are presented. The aim of the paper is to show how such SPH simulations of complex 3D problems involving a free surface can be performed on a super computer like the IBM Blue Gene/L with 8,192 cores of Ecole polytechnique fédérale de Lausanne. The present paper thus presents the different techniques which had to be included into the SPH model to make possible such simulations. Memory handling, in particular, is a quite subtle issue because of constraints due to the use of a variable-h scheme. These improvements made possible the simulation of test cases involving hundreds of million particles computed by using thousands of cores. Speedup and efficiency of these parallel calculations are studied. The model capabilities are illustrated in the paper for two water entry problems, firstly, on a simple test case involving a sphere impacting the free surface at high velocity; and secondly, on a complex 3D geometry involving a ship hull impacting the free surface in forced motion. Sensitivity to spatial resolution is investigated as well in the case of the sphere water entry, and the flow analysis is performed by comparing both experimental and theoretical reference results.

The purpose of this work is to evaluate the use of the smoothed particle hydrodynamics (SPH) method within the framework of high speed cutting modelling. First, a 2D SPH based model is carried out using the LS-DYNA® software. The developed SPH model proves its ability to account for continuous and shear localised chip formation and also correctly estimates the cutting forces, as illustrated in some orthogonal cutting examples. Then, the SPH model is used in order to improve the general understanding of machining with worn tools. At last, a hybrid milling model allowing the calculation of the 3D cutting forces is presented. The interest of the suggested approach is to be freed from classically needed machining tests: Those are replaced by 2D numerical tests using the SPH model. The developed approach proved its ability to model the 3D cutting forces in ball end milling.

Numerical investigations on bionic propulsion problems using the multi-resolution Delta-plus SPH model

In the last chapter, the Smoothed Particle Hydrodynamics (SPH) procedure based on hydrodynamics and elasto-plastic mechanics was developed for geo-disaster modeling. In this chapter, a series of validations for the SPH computer procedure are conducted. For the hydrodynamics SPH programs, the dam-break model and soil flow model tests are simulated, and the results are compared with those from the literature to determine the accuracy of SPH. For the SPH procedure in the framework of solid mechanics, a simple shear test of perfect elasticity and elasto-plastic material is simulated, and simulated stress–strain relationships are compared with the analytical solution and finite element method (FEM) results, thereby verifying the SPH models.

SPH study of scale effects of perforated caissons

Static and dynamic characteristics of a downsized aerostatic circular thrust bearing with a single feed hole

This review article presents key aspects of applying Smoothed Particle Hydrodynamics (SPH) to model fluid filtration through FDM 3D-printed copper-based filters (80% Cu, 20% PLA composite filament) with microporosity. Conservation laws in continuum dynamics form the foundation of meshless SPH modeling. The complexity of modeling 3D printed copper-based filters lies in capturing the irregular shapes of microporosity. We present an initial SPH model that provides velocity and pressure distributions through a round pore, demonstrating better accuracy than the FEM model. Such SPH approach can accurately capture water flow parameters through complex porous structures. Unlike FEM, which relies on predefined finite elements, SPH is a Lagrangian method based on the distribution of virtual particles and periodic boundary conditions, making it well-suited for modelling irregular geometries. Combined with 3D printing, SPH can support the design of optimal structures for water filtration.

Abstract. Flow-like landslides, such as flow slides and debris avalanches, have caused serious infrastructure damage and casualties for centuries. Effective numerical simulation incorporating accurate soil mechanical parameters is essential for predicting post-failure landslide mobility. In this study, smoothed particle hydrodynamics (SPH) incorporating soil ring shear test results were used to forecast the long-runout mobility for a landslide on an unstable slope in China. First, a series of ring shear tests under different axial stresses and shear velocities were conducted to evaluate the residual shear strength of slip zones after extensive shear deformation. Based on the ring shear test results, SPH modeling was conducted to predict the post-failure mobility of a previously identified unstable slope. The results indicate that the landslide would cut a fire service road on the slope after 12 s and cover an expressway at the foot of that slope after 36 s. In the model, the landslide would finally stop sliding about 38 m beyond the foot of the slope after 200 s. This study extends the application of the SPH model from disaster simulations to predictive analysis of unstable landslide. In addition, two sets of comparative calculations were carried out which demonstrate the robustness of the SPH method.

A numerical study of a vertical axis wind turbine was performed using commercial computational fluid dynamics (CFD) software ANSYS CFX. Normal and tangential force coefficients were compared to measurements for two tip speed ratios. The CFD results generally had a good agreement with the experimental results, with more discrepancies for the tangential coefficient than the normal coefficient, likely due to its lower magnitude. For the higher tip speed ratio, CFD simulations were run with both no-slip and free-slip boundary conditions on the airfoils, and were found to produce comparable results. The CFD predictions were also compared with a vortex filament method code, with which there was generally a good agreement. Overall the CFD model seemed to produce acceptable predictions for the normal and tangential force coefficients. This work could be used as a framework for future simulations in the testing of novel Darrieus wind turbine designs.