Finite Element-Based Boundary Treatment in the Hybrid Particle Method

We developed a method of hybrid particle/cubic interpolated propagation (CIP) to predict the motion of micro- and macrofree surfaces within gas-liquid flows. Microfree surfaces (smaller than the grid sizes) were simulated with the particle method, and macrofree surfaces (larger than the grid sizes) were simulated with the grid method (CIP is a kind of grid method). With the hybrid, velocities given by the advection part of the particle method were combined with those given by the advection part of CIP. Furthermore, the particles used with the particle method were assigned near the macrofree surfaces by using the volume fraction of liquid that was calculated with CIP. The method we developed was used to predict the collapse of a liquid column. Namely, it was simultaneously able to predict both large deformation in the liquid column and its fragmentation, and the predicted configurations for the liquid column agreed well with the experimentally measured ones. It was also used to predict the behavior of liquid films at the outlet of a fuel injector used for automobile engines. The particle method in the simulation was mainly used for liquid films in the air region and the grid method was used for the other regions to shorten the computational time. The predicted profile of the liquid film was very sharp in the air region where the liquid film became thinner than the grid sizes; there was no loss of liquid film with numerical diffusion.

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Numerical Simulation of Hypervelocity Impact FEM-SPH Algorithm Based on Large Deformation of Material

10.20944/preprints201610.0055.v1 ◽

2016 ◽

Cited By ~ 1

Author(s):

Aimin Yang ◽

Jinze Li ◽

Hengheng Qu ◽

Yuhang Pan ◽

Yanhong Kang ◽

...

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Large Deformation ◽

Particle Method ◽

The Finite Element Method ◽

Smoothed Particle ◽

Sph Algorithm ◽

Coupling Algorithm ◽

Large Deformation Problems ◽

Element Method

In this paper, we first discuss the research status and application progress of the finite element method and the smoothed particle method. By analyzing the advantages of the smoothed particle method and the finite element method, a new coupling algorithm, namely FEM-SPH algorithm, is proposed. By the method of comparison, it shows that finite element method and SPH method in the simulation of large deformation problems each have advantages and disadvantages, the finite element method smoothed particle coupling algorithm is effective to achieve the performance of high computational efficiency and can naturally simulate large deformation problems across. In the process of calculation, the large deformation unit can be freely into an algorithm to facilitate the calculation accuracy and efficiency of three methods of numerical simulation. Through the study found, FEM-SPH algorithm not only overcome the defect of smooth particle tensile instability, but also overcomes the problem of low efficiency of finite element computation. To further test the FEM-SPH algorithm has advantages in the practical engineering, we have carried out the actual test to the example of the super high speed collision, concluded that, since the target of most of the computational domain is always finite element, smoothed particle focused only in contact with the projectile and target of local area, particle number is not much, the whole calculation process just ten minutes, computational efficiency has been greatly improved, at the same time in the simulation of large deformation, the advantage is very obvious .This provides a criterion for the actual project, depending on the specific material deformation mode and choose a more appropriate conversion algorithm.

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Spatial thin-walled reinforced concrete structures taking into account physical nonlinearity in SCAD software. Rod finite element

The proceedings of the 13th international conference "Modern Building Materials, Structures and Techniques" (MBMST 2019) ◽

10.3846/mbmst.2019.086 ◽

2019 ◽

Author(s):

Sergiy Fialko ◽

Viktor Karpilowskyi

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Plastic Flow ◽

Deformation Theory ◽

Numerical Solutions ◽

Experimental Studies ◽

Particle Method ◽

Reinforced Concrete Beams ◽

Principal Stresses ◽

Theory Of Plasticity

This paper considers a spatial frame bar finite element for modeling reinforced concrete beams and columns. Both concrete and reinforcement are described by the equations of the deformation theory of plasticity and the theory of plastic flow. Degradation of concrete during cracking is modeled by the descending branch of the σ – ε diagram (the deformation theory of plasticity), as well as the compression of the yield surface and its displacement in the space of principal stresses (the plastic flow theory). The longitudinal reinforcement is considered discretely. It is assumed that there is no reinforcement slipping in concrete. The paper provides the results of the studies that reveal the causes of computational instability related to the presence of a descending branch of the σ – ε diagram for concrete, and proposes ways to overcome it. The reliability of the obtained results is confirmed by comparing them with the results of experimental studies performed by other researchers, as well as with the results of numerical solutions obtained by the particle method. This paper also provides an example of the nonlinear analysis of the fragment of a multi-storey building from the SCAD Soft collection of problems (www.scadsoft.com).

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Modeling Sound Propagation Using the Corrective Smoothed Particle Method with an Acoustic Boundary Treatment Technique

10.20944/preprints201701.0067.v1 ◽

2017 ◽

Author(s):

YongOu Zhang ◽

Xu Li ◽

Tao Zhang

Keyword(s):

Boundary Conditions ◽

Time Domain ◽

Sound Propagation ◽

Fdtd Method ◽

Particle Method ◽

Absorbing Boundary Conditions ◽

Treatment Technique ◽

Sph Method ◽

Boundary Treatment ◽

Smoothed Particle

The development of computational acoustics allows simulation of sound generation and propagation in complex environment. In particular, meshfree methods are widely used to solve acoustics problems through arbitrarily distributed field points and approximation smoothness flexibility. As a Lagrangian meshfree method, smoothed particle hydrodynamics (SPH) method reduce the difficulty in solving problems with deformable boundaries, complex topologies, or multiphase medium. The traditional SPH method has been applied in acoustic simulation. This study presents the corrective smoothed particle method (CSPM), which is a combination of SPH kernel estimate and Taylor series expansion. The CSPM is introduced as a Lagrangian approach to improve accuracy in solving acoustic wave equations in the time domain. Moreover, a boundary treatment technique based on the hybrid meshfree and finite difference time domain (FDTD) method is proposed to represent different acoustic boundaries with particles. To model sound propagation in pipes with different boundaries, soft, rigid, and absorbing boundary conditions are built with this technique. Numerical results show that the CSPM algorithm is consistent and demonstrates convergence with exact solutions. Main computational parameters are discussed, and different boundary conditions are validated to be effective for benchmark problems in computational acoustics.

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