scholarly journals An Anti-Clustering Model for Stability Enhancement of a 3D Moving Particle Semi-Implicit Method and Two-Phase Coupling between MPS and Euler Grids

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 887
Author(s):  
Meiyan Feng ◽  
Shenghong Huang ◽  
Guofu Lian
Keyword(s):  
Fluid Model ◽  
High Order ◽  
Implicit Method ◽  
Particle Clustering ◽  
Positive Role ◽  
Simulation Accuracy ◽  
Mps Method ◽  
Clustering Model ◽  
Moving Particle ◽  
Stability Enhancement

As a Lagrangian gridless particle method, the MPS (Moving Particle Semi-implicit) method has a wide engineering application. However, for complex 3D flows, unphysical pressure oscillations often occur and result in the failure of simulations. This paper compares the stability enhancement methods proposed by different researchers to develop a 3D, stable MPS method. The results indicate that the proposed methods are incapable of eliminating the particle clustering that leads to instability as the main source in coarser particle spacing cases. An anti-clustering model, referring to the SPH (Smoothed Particle Hydrodynamics) artificial viscosity model, is proposed to further reduce instability. Combining various proposed methods and models, several typical examples are simulated comparatively. The results are compared with those of the VOF (Volume of Fluid) model using commercial software to validate the accuracy and stability of the combination of the proposed methods and models. It is concluded that (1) 3D cases that adopt a high-order Laplacian model and high-order source terms in PPE are more accurate than those adopting the low-order operators; (2) the proposed anti-clustering model can produce a tuned interparticle force to prevent particle clustering and introduce no additional viscosity effects in the flow of the normal state, which plays a very positive role for further stability enhancement of MPS; (3) particle resolution significantly maintains simulation accuracy given the stable algorithms by the combination of stability enhancement methods. The 3D MPS method is coupled with the Euler grid (FLUENT V17 software, ANSYS, Pittsburgh, PA, USA) in two phases. In particular, the 3D MPS algorithm is used to calculate the liquid-phase change from the continuous to the dispersed, and the finite volume method based on the Euler grid is adopted to measure the corresponding gas-phase motion. The atomization of the liquid jet under static air flow is calculated and compared with the results of the VOF method, which can capture the continuous interface.

Simulation of the Mooring Vessels in Tsunamis Using the MPS Method Considers Leading Wave and Backwash

2012 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda ◽  
Tomoki Ikoma
Keyword(s):  
Experimental Results ◽  
Implicit Method ◽  
Present Calculation ◽  
Mps Method ◽  
Calculation Results ◽  
Moving Particle

The present paper describes the simulation of behavior of mooring vessels in tsunami using the 3-D MPS (Moving Particle Semi-implicit) Method for considering leading wave and backwash effect. The chain of a disaster is brought about by two kinds of tsunami. The chain of disaster means breaking the mooring tether, grounding on a wharf, drift to continental areas, the collision with building by leading wave and the outflow of the floating matter by backwash. In this research, the 3D-MPS method is applied, and the bore like wave is applied as an assumed tsunami. The expression of backwash is tried by water pillar collapse. The present calculation results are compared with the experimental results and the applicability of the MPS method is discussed. In addition, the vehicle is arranged on a wharf, and the chain of disaster is simulated.

Effects of Wall Condition of a Plunging Body on Splash

2011 ◽  
Author(s):  
Masao Yokoyama ◽  
Yoshihiro Kubota ◽  
Osamu Mochizuki
Keyword(s):  
Numerical Simulation ◽  
Implicit Method ◽  
Water Tank ◽  
Air Cavity ◽  
Slip Ratio ◽  
Mps Method ◽  
Swelling Degree ◽  
Living Things ◽  
Wall Condition ◽  
Moving Particle

Splashes generated by hydrogel sphere were simulated numerically and experimentally for investigating the effects of slip like mucus of living things. Numerical simulation using MPS (Moving Particle Semi-implicit) method was carried out. We defined the slip ratio as the swelling degree of hydrogel and installed the slip ratio into the MPS method. The swelling degree is the ratio of the weight of water against that of hydrogel. We simulated the splashes generated by the hydrogel spheres which had the different swelling degree plunging into water. As the evaluation of swelling degree on the surface of actual hydrogel spheres we also tested by using the hydrogel spheres plunging into water experimentally. The height of splash as a result of reaction of the air cavity became higher according to the increase of the swelling degree. The speed of hydrogel sphere sinking in water tank was also quicker in the numerical simulation. The reason of these results was that the velocity of water around the hydrogel sphere became quicker due to the slip on the surface.

Simulation of Red Blood Cell Passing Through Constrictions Using Modified Moving Particle Semi-Implicit Method

2011 ◽  
Author(s):  
K. Firoozbakhsh ◽  
M. T. Ahmadian ◽  
M. Hasanian
Keyword(s):  
Mechanical Behavior ◽  
Experimental Studies ◽  
Small Time ◽  
Implicit Method ◽  
Parallel Plates ◽  
Time Step ◽  
Mps Method ◽  
Time Step Size ◽  
Small Time Step ◽  
Moving Particle

During the circulation of RBC it undergoes elastic deformation as it passes through micro-capillaries where the inner diameter of the constriction can be about 3 micro meters. It means RBC shape must be changed in order to pass through these narrow channels. The role of mechanical behavior of RBC and the deformability traits of RBC are observed with the several experimental studies [1]. Several methods were implemented to simulate the mechanical behavior of RBCs in micro-capillaries [1, 2]. One of the most recent methods is Moving Particle Semi-implicit method (MPS) which is a Lagrangian method with semi-implicit algorithm that guaranties the incompressibility of the fluid. MPS method was implemented for simulation of RBC motion through parallel plates by Tsubota et al. 2006 [3]. Due to small Reynolds number and the Diffusion number restrictions, implementation of small time step size would be necessary which leads to long time simulation. By the way in case of complex geometries or FSI problems, standard MPS method has a delicate pressure solver which leads to diverge the solution. So in these cases using a small time step can help to overcome the problem. Some studies have applied a new approach for time integration and the fractional time step method is employed to overcome the noticed problem. Yohsuke Imai and coworkers (2010) have developed the former studies with two main new approaches [4]. Firstly, evaluation of viscosity is upgraded and secondly boundary condition is assumed to be periodic. Although the developments are really impressive and MPS method has turned into a practical method for simulation of RBC motion in micro-capillaries, but still there are some considerations about using large time steps and error of the velocity profile consequently.

A Fundamental Study on the Damage of Wash Up to the Quay of the Moored Vessel in Tsunamis Using the MPS Method Considered the Fender Influences

2018 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Simulation Method ◽  
Implicit Method ◽  
Spring Model ◽  
Mooring Lines ◽  
Fundamental Study ◽  
Protection Measures ◽  
Mps Method ◽  
Moving Particle

In the case of vessels are moored at the quay, the drift and the wash up to the quay due to the broke of mooring lines is occurred by the tsunamis. In the previous study, the authors are examined to the applicability of the proposed tsunami protection measures as the install more mooring lines (IMML) and the floating tsunami protection wharf (FTPW). However, the Fender influences were not considered in previous authors studies. In this study, the fender influences are considered on the numerical simulation. The three-dimensional MPS (Moving Particle Semi-implicit) method is used as numerical simulation method. The linear compressing spring model is used as the fender model. The fender influences were investigated against the influences of tsunami protection measures using IMML and the damage status of vessel.

scholarly journals LNG Tank Sloshing Simulation of Multidegree Motions Based on Modified 3D MPS Method

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Chunhui Wang ◽  
Chunyu Guo ◽  
Fenglei Han
Keyword(s):  
Free Surface ◽  
Weighted Average ◽  
Kernel Functions ◽  
Computational Stability ◽  
Mps Method ◽  
Fluid Sloshing ◽  
Particle Hydrodynamics ◽  
Moving Particle ◽  
Lng Tank ◽  
Stability And Accuracy

Modified 3D Moving Particle Semi-Implicit (MPS) method is used to complete the numerical simulation of the fluid sloshing in LNG tank under multidegree excitation motion, which is compared with the results of experiments and 2D calculations obtained by other scholars to verify the reliability. The cubic spline kernel functions used in Smoothed Particle Hydrodynamics (SPH) method are adopted to reduce the deviation caused by consecutive two times weighted average calculations; the boundary conditions and the determination of free surface particles are modified to improve the computational stability and accuracy of 3D calculation. The tank is under forced multidegree excitation motion to simulate the real conditions of LNG ships, the pressures and the free surfaces at different times are given to verify the accuracy of 3D simulation, and the free surface and the splashed particles can be simulated more exactly.

A domain decomposition strategy for hybrid parallelization of moving particle semi-implicit (MPS) method for computer cluster

2015 ◽  
Vol 18 (4) ◽  
pp. 1363-1377 ◽  
Author(s):  
Davi Teodoro Fernandes ◽  
Liang-Yee Cheng ◽  
Eric Henrique Favero ◽  
Kazuo Nishimoto
Keyword(s):  
Domain Decomposition ◽  
Computer Cluster ◽  
Mps Method ◽  
Hybrid Parallelization ◽  
Moving Particle

Optimization of Moving Particle Semi-Implicit (MPS) Method and Studying of Flow Instability

2018 ◽  
Author(s):  
Kailun Guo ◽  
Ronghua Chen ◽  
Suizheng Qiu ◽  
Wenxi Tian ◽  
Guanghui Su ◽  
...  
Keyword(s):  
Multiphase Flows ◽  
Flow Instability ◽  
Free Particle ◽  
Particle Method ◽  
Severe Accident ◽  
Particle Methods ◽  
Two Phase ◽  
Mps Method ◽  
Viscosity Term ◽  
Moving Particle

Multiphase flow widely exists in the nature and engineering. The two-phase flow is the highlight of the studies about the flow in the vessel and steam explosion in nuclear severe accidents. The Moving Particle Semi-implicit (MPS) method is a fully-Lagrangian particle method without grid mesh which focuses on tracking the single particle and concerns with its movement. It has advantages in tracking complex multiphase flows compared with gird methods, and thus shows great potential in predicting multiphase flows. The objective of this thesis is to develop a general multiphase particle method based on the original MPS method and thus this work is of great significance for improving the numerical method for simulating the instability in reactor severe accident and two-phase flows in vessel. This research is intended to provide a study of the instability based on the MPS method. Latest achievements of mesh-free particle methods in instability are researched and a new multiphase MPS method, which is based on the original one, for simulating instability has been developed and validated. Based on referring to other researchers’ papers, the Pressure Poisson Equation (PPE), the viscosity term, the free surface particle determination part and the surface tension model are optimized or added. The numerical simulation on stratification behavior of two immiscible flows is carried out and results are analyzed after data processing. It is proved that the improved MPS method is more accurate than the original method in analysis of multiphase flows. In this paper, the main purposes are simulating and discussing Rayleigh-Taylor (R-T) instability and Kelvin-Helmholtz (K-H) instability. R-T and K-H instability play an important role in the mixing process of many layered flows. R-T instability occurs when a lower density fluid is supported by another density higher fluid or higher density fluid is accelerated by lower density fluid, and the resulting small perturbation increases and eventually forms turbulence. K-H instability is a small disturbance for two different densities, such as waves, at the interface of the two-phase fluid after giving a fixed acceleration in the fluid. Turbulence generated by R-T instability and K-H instability has an important effect in applications such as astrophysics, geophysics, and nuclear science.

Simulation of Multiliquid-Layer Sloshing With Vessel Motion by Using Moving Particle Semi-Implicit Method

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Kyung Sung Kim ◽  
Moo-Hyun Kim ◽  
Jong-Chun Park
Keyword(s):  
Gas Production ◽  
Particle Simulation ◽  
Small Scale ◽  
Linear Potential ◽  
Operational Effectiveness ◽  
Mps Method ◽  
Moving Particle ◽  
Vessel Motion ◽  
Linear Potential Theory ◽  
Oil Gas

For oil/gas production/processing platforms, multiple liquid layers can exist and their respective sloshing motions can also affect operational effectiveness or platform performance. To numerically simulate those problems, a new multiliquid moving particle simulation (MPS) method is developed. In particular, to better simulate the relevant physics, robust self-buoyancy model, interface searching model, and surface-tension model are developed. The developed multiliquid MPS method is validated by comparisons against experiment in which three-liquid-sloshing experiment and the corresponding linear potential theory are given. The validated multiliquid MPS program is subsequently coupled with a vessel-motion program in time domain to investigate their dynamic-coupling effects. In case of multiple liquid layers, there exists a variety of sloshing natural frequencies for respective interfaces, so the relevant physics can be much more complicated compared with the single-liquid-tank case. The simulation program can also reproduce the detailed small-scale interface phenomenon called Kelvin–Helmholtz instability. The numerical simulations also show that properly designed liquid cargo tank can also function as a beneficial antirolling device.

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