Papers by Keyword: Smoothed Particle Hydrodynamic (SPH)

Abstract: Study on the load exerted on cutter head is very useful for the design and performance prediction of hard rock tunnel boring machines. A composite model based on smoothed particle hydrodynamics and finite element method was carried out using AUTODYN software to study the rock fragmentation mechanism of constant cross-section disk cutters in cutter head. The normal force, rolling force and side force on the disk cutters with different cutter radius were researched in the numerical simulation study. The results were verified by historical literature data. To obtain the distribution of the forces with different cutter radius, the loading of cutter head of a Ф5.75 hard rock tunnel boring machine were analyzed. The result shows that it is useful for cutter head’s design and its layout optimization.

Abstract: It is significant for the phenomena of bouncing on water to analyze the ditching procedure of any kind of aircraft. The SPH method is employed to achieve a numerical simulation in the architecture of LS-DYNA and PrePost programs. The water domain is modeled by SPH and the boundary condition is discussed too. Through a set of contrastive analysis of different boundary conditions, some constructive suggestions of establishing the boundary conditions are given to deeply simulate aircraft ditching in the future.

Abstract: The material removal in ultrasonic machining (USM) is based on brittle fracturing of workpiece materials. The properties and fracture behavior are different for varied materials, and they would have an influence on the machining performance of USM. The smoothed particle hydrodynamics (SPH) method was used to simulate the USM process for different workpiece materials. Three typical hard and brittle materials, i.e. silicon carbide (SiC), alumina (Al₂O₃), and glass will be used as the workpiece materials. Experiments are also conducted for comparing with the simulation results. Through this study, the material fracturing processes for different work materials are shown visually using the SPH method, which is very useful for USM study.

Abstract: Water jet technology is widely used in dredging engineering. Since there will be large deformation of sand bed during erosion by water jet, the calculation mesh will be distorted seriously and lead to simulation failure. In order to solve the problem, the Smoothed Particle Hydrodynamics (SPH) method was used to simulate the dynamic process of high speed water jet erosion of sand bed. The simulation process and key techniques were discussed, the effect of water jet velocity and water jet target distance on the depth of eroded pit was studied. The results show that SPH could describe the process intuitively and the evolution of particle velocity field and sand bed pressure field could be shown clearly. The depth of the pit varies with time linearly. The decrease of water jet target distance and the increase of the water jet velocity deepen the eroded pit.

Abstract: The distortion of particles distribution is a defect that usually leads to numerical instability in the traditional SPH method. In this contribution, we introduce a novel local regrouping method to solve this problem. The basic idea is to keep the particles undeformed by regrouping, dividing or combining the deformed particles. We succeed to simulate the Taylor-Green vortex in 2D with this method, and demonstrate the effectiveness of this method.

Abstract: A model for the deformation of fluid particle under the action of velocity gradient tensor is proposed in this article. In this contribution, the control volume/surface is geometrically simplified into micro-ellipse. By using a series of changes of basis and eigenvalue decomposition, a numerical method for the deformation of an elliptic fluid particle is then demonstrated. Finally, this method is applied in two different problems involving smoothed particle hydrodynamics (SPH) simulation and a passive scalar turbulence case.

Abstract: Liquid-Driven Stretch Blow Molding is a new and innovative method to produce PET bottles [. In the well-established Stretch Blow Molding (SBM) process, preforms are biaxially deformed by pressurized air into a cavity. The resulting bottles are transferred to a separate machine, where the desired product is filled in. In contrast to that, Liquid-Driven Stretch Blow Molding is characterized by employing the liquid product to deform the material. The former separated blowing and filling steps are thus combined to a single forming stage leading to numerous advantages in energy consumption, cycle time and machine footprint. In this paper, a numerical simulation of the new process is presented. An additional challenge compared to SBM simulations is thereby the consideration of the interaction between liquid and preform. The load application cannot be solely represented by the pressure because the influx behavior as well as gravity and inertia forces influence the preform deformation. A smoothed particle hydrodynamics (SPH) approach is applied to the simulation to incorporate the additional effects. The process model is evaluated by prototype experiments. In addition, a feasibility study shows the applicability of a rotary forming system to the new process.

Abstract: The study concerns the application of the smoothed particle hydrodynamics (SPH) method within computational fluid dynamics. In the present study, a tank discharge with a falling head is investigated. Water is modelled as a viscous fluid with weak compressibility. An enhanced treatment of the solid boundaries is used within the two-dimensional SPH scheme. The boundaries are represented by a special set of SPH particles that differ from the ones representing the fluid by being immovable, preventing the fluid from leaving the container. Particles with different colors are used to illustrate the sequence of the empting the tank as well as the velocity vectors to show stream lines. A code is developed using C++ to solve all equations explicitly by use of a Verlet algorithm. Results are compared to an analytical solution, and a good agreement is achieved.

Abstract: In this paper we present a brief comparison of existing equation of state laws used inSmoothed Particle Hydrodynamics (SPH) and introduce some new expressions for the equation ofstate for pressure, as well as to calculate temperature. In SPH literature practical examples of heatconduction and energy are scarce when compared with fluid flow formulations that determine pressuresimply from density and an artificial speed of sound. Such simplifications may be appropriate forisothermal flow problems; however, a more thermodynamically rigorous formulation is necessary forcomplex and thermally driven problems, particularly in geophysics. This work discusses conventionalequations of state, as well as presenting some new relations. This includes having pressure depend onthe energy of the system, and applying these relations to a number of proof of concept examplesdemonstrating natural convection and examining the parameters of the new equation of state. Thesedevelopments facilitate future work towards modelling more complex physical phenomena such asheat driven convective flow.

Abstract: Landslides are among the most devastating natural hazards because they often initiate rapidly and mobilize very large volumes of material. While the mechanics of landslides is relatively well understood it is still extremely difficult to anticipate any particular event and estimate its potential consequences. Mesh-free methods are ideally suited to handle large deformations associated with slope failure but they often assume the mechanism of failure a priori. In this work we apply Smoothed Particle Hydrodynamics to simulate all phases of a landslide within one single numerical platform. A Drücker-Prager model is used to determine the onset of failure. The post-failure behaviour is accommodated naturally by the mesh-free nature of the method. The relevance of the method to the modelling of landslides is demonstrated on several examples of slope failure.