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.

3D Simulation of Molten Metal Freezing Behaviour Using Finite Volume Particle Method

2010 ◽  
Author(s):  
Rida S. N. Mahmudah ◽  
Masahiro Kumabe ◽  
Takahito Suzuki ◽  
LianCheng Guo ◽  
Koji Morita ◽  
...  
Keyword(s):  
Molten Metal ◽  
Finite Volume ◽  
Particle Method ◽  
Metal Structure ◽  
Freezing Behavior ◽  
Severe Accident ◽  
Particle Methods ◽  
Freezing Process ◽  
Penetration Length ◽  
Moving Particle

Understanding the freezing behavior of molten metal in flow channels is of importance for severe accident analysis of liquid metal reactors. In order to simulate its fundamental behavior, a 3D fluid dynamics code was developed using Finite Volume Particle (FVP) method, which is one of the moving particle methods. This method, which is fully Lagrangian particle method, assumes that each moving particle occupies certain volume. The governing equations that determine the phase change process are solved by discretizing its gradient and Laplacian terms with the moving particles. The motions of each particle and heat transfer between particles are calculated through interaction with its neighboring particles. A series of experiments for fundamental freezing behavior of molten metal during penetration on to a metal structure was also performed to provide data for the validation of the developed code. The comparison between simulation and experimental results indicates that the present 3D code using the FVP method can successfully reproduce the observed freezing process such as molten metal temperature profile, frozen molten metal shape and its penetration length on the metal structure.

Numerical Analysis of the Corium Behavior Within the Fuel Support Piece by MPS

2016 ◽  
Author(s):  
Ronghua Chen ◽  
Lie Chen ◽  
Wenxi Tian ◽  
Guanghui Su ◽  
Suizheng Qiu
Keyword(s):  
Eutectic Reaction ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Severe Accident ◽  
Guide Tube ◽  
Melt Flow ◽  
Control Rod ◽  
Mps Method ◽  
Moving Particle ◽  
Accident Conditions

In the typical boiling water reactor (BWR), each control rod guide tube supports four fuel assemblies via an orificed fuel support piece in which a channel is designed to be a potential corium relocation path from the core region to the lower head under severe accident conditions. In this study, the improved Moving Particle Semi-implicit (MPS) method was adopted to analyze the melt flow and ablation behavior in this region during a severe accident of BWR. A three-dimensional particle configuration was constructed for analyzing the melt flow behavior within the fuel support piece. Considering the symmetry of the fuel support piece, only one fourth of the fuel support was simulated. The eutectic reaction between Zr (the material of the corium) and stainless steel (the material of the fuel support piece) was taken into consideration. The typical melt flow and freezing behaviors within the fuel support piece were successfully reproduced by MPS method. In all the simulation cases, the melt discharged from the hole of the fuel support piece instead of plugging the fuel support piece. The results indicate that MPS method has the capacity to analyze the melt flow and solidification behavior in the fuel support piece.

Numerical Study of Fuel Melting and Molten Migration Based on the MPS Method

2020 ◽  
Author(s):  
Zhong Lei ◽  
Jian Deng ◽  
Wei Li ◽  
Xiaoli Wu ◽  
Chunrui Deng
Keyword(s):  
Nuclear Reactor ◽  
Initial Temperature ◽  
Numerical Study ◽  
Eutectic Reaction ◽  
Melting Process ◽  
Severe Accident ◽  
Migration Behavior ◽  
Mps Method ◽  
Water Reactors ◽  
Moving Particle

Abstract Core melting and molten migration behavior are hot and difficult issues in the field of nuclear reactor severe accident research. The Moving Particle Semi-implicit (MPS) meshless method has potential to simulate free-surface and multiphase flows. In this study, the MPS method was utilized to simulate the melting process of UO2-Zr rod-type fuel elements. The models of heat conduction with phase change, simplified UO2-Zr eutectic reaction, viscous flow and surface tension were implemented with the framework of standard MPS method. Then, the improved MPS code was used to simulate and analyze the process of high-temperature melting and characteristics of molten migration and solidification in the coolant channel, aiming at revealing the severe accidents for light water reactors (LWR), particularly the early core damage. The results showed that compared with the case of higher initial temperature, when the initial temperature of molten UO2 is lower, more molten UO2 will solidify on the surface of rod cluster, and the blockage of upper flow channel caused by molten UO2 is more serious. In addition, this study also demonstrated the potential of the MPS method for the study of complicated severe accident phenomena in not only traditional LWR but also advanced nuclear reactors in the future.

Stable Moving Particle Semi Implicit Method for Modeling Waves Generated by Submarine Landslides

2014 ◽  
Author(s):  
Mohammad Amin Nabian ◽  
Leila Farhadi
Keyword(s):  
Water Surface ◽  
Surface Profile ◽  
Particle Methods ◽  
Water Tank ◽  
Submarine Landslides ◽  
Fractional Step Method ◽  
Time Step ◽  
Mps Method ◽  
Water Surface Profile ◽  
Moving Particle

A mesh-free numerical formulation, known as Moving Particle Semi Implicit (MPS) Method, is used for modeling waves generated by submarine landslides. In this formulation, approximations are provided to the strong form of PDEs on the basis of integral interpolants. The governing equations, Navier-Stokes equations, are solved in a 2D fully Lagrangian form. This method utilizes a fractional step method and splits each time step in two steps. The fluid is represented with particles and the motion of each particle is calculated through interactions with neighboring particles by means of a kernel function. Landslides in this paper are simulated by a submerged triangle rigid wedge sliding along an inclined plane into a water tank. As the wedge sinks, a wave and a vortex is formed. The water surface profile, velocity field and pressure field are represented at different times. To confirm the accuracy of the model, the water surface profile is compared with the experimental data, showing good agreement. Simulations can continue for a long period of time without any instability occurrence and this is a remarkable competency amongst other particle methods. A discussion on multi-size particle strategy and its ability to increase the efficiency of MPS method is provided at the end of the paper.

scholarly journals Sloshing Simulation of Single-Phase and Two-Phase SPH using DualSPHysics

Kapal ◽  
2020 ◽  
Vol 17 (2) ◽  
pp. 50-57
Author(s):  
Andi Trimulyono ◽  
S Samuel ◽  
Muhammad Iqbal
Keyword(s):  
Free Surface ◽  
Pressure Sensors ◽  
Pressure Oscillation ◽  
Particle Method ◽  
Surface Flow ◽  
Particle Methods ◽  
Two Phase ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

The sloshing phenomenon is one of the free surface flow that can endanger liquid cargo carriers such as ships. Sloshing is defined as the resonance of fluid inside a tank caused by external oscillation. When sloshing is close to the natural frequency of the tank it could endanger ships. Particle method has the advantages to be applied because sloshing is dealing with free surface. One of the particle methods is Smoothed Particle Hydrodynamics (SPH). In this study, compressible SPH was used as a result of the pressure oscillation, which exists because of the effect of density fluctuation as nature of weakly compressible SPH. To reduce pressure noise, a filtering method, Low Pass Filter,  was used to overcome pressure oscillation. Three pressure sensors were used in the sloshing experiment with a combination of motions and filling ratios. Only one pressure sensor located in the bottom was used to validate the numerical results. A set of SPH parameters were derived that fit for the sloshing problem. The SPH results show a good agreement with the experiment’s. The difference between SPH and experiment is under 1 % for sway, but a larger difference shows in roll. Low pass filter technique could reduce pressure noise, but comprehensive method needs to develop for general implementation.

Numerical Simulation of Jet Breakup Using Particle Method

2003 ◽  
Author(s):  
S. Koshizuka ◽  
K. Shibata ◽  
Y. Oka
Keyword(s):  
Weber Number ◽  
Differential Operators ◽  
Particle Interaction ◽  
Particle Method ◽  
Two Dimensions ◽  
Particle Interactions ◽  
Governing Equations ◽  
Mps Method ◽  
Jet Breakup ◽  
Moving Particle

Numerical analysis of jet breakup is carried out using Moving Particle Semi-implicit (MPS) method in x-y two dimensions. In the MPS method, particle interaction models are prepared for differential operators and the governing equations are discretized without grids. Surface tension is also modeled as particle interactions. Effects of the Weber number and the Froude number on the jet breakup length agree well with experimental data.

A NUMERICALLY CONSISTENT MULTIPHASE POISEUILLE FLOW COMPUTATION BY A NEW PARTICLE METHOD

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
K. C. Ng ◽  
Y. H. Hwang ◽  
T. W. H. Sheu ◽  
M. Z. Yusoff
Keyword(s):  
Fluid Flow ◽  
Poiseuille Flow ◽  
Particle Method ◽  
Numerical Approach ◽  
Particle Methods ◽  
Diffusion Term ◽  
Flow Solver ◽  
Mesh Free ◽  
Consistent Method ◽  
Moving Particle

Recently, there is a rising interest in simulating fluid flow by using particle methods, which are mesh-free. However, the viscous stresses (or diffusion term) appeared in fluid flow governing equations are commonly expressed as the second-order derivatives of flow velocities, which are usually discretized by an inconsistent numerical approach in a particle-based method. In this work, a consistent method in discretizing the diffusion term is implemented in our particle-based fluid flow solver (namely the Moving Particle Pressure Mesh (MPPM) method). The new solver is then used to solve a multiphase Poiseuille flow problem. The error is decreasing while the grid is refined, showing the consistency of our current numerical implementation.

Numerical Simulation of 3D Liquid Sloshing Motion With Solid Particles Using Finite Volume Particle Method

2010 ◽  
Author(s):  
LianCheng Guo ◽  
Shuai Zhang ◽  
Koji Morita ◽  
Kenji Fukuda
Keyword(s):  
Solid Particle ◽  
Finite Volume ◽  
Liquid Mixture ◽  
Particle Method ◽  
Solid Particles ◽  
Liquid Sloshing ◽  
Particle Methods ◽  
3D Motion ◽  
Sloshing Dynamics ◽  
Moving Particle

Sloshing dynamics of a molten core is one of the fundamental behaviors in core disruptive accidents of a liquid-metal cooled reactor. In addition, solid particle-liquid mixture comprising molten fuel, molten structure, refrozen fuel, solid fuel pellets, etc. could lead to damping of its flowing process in a disrupted core. The objective of the present study is to investigate the applicability of the finite volume particle method (FVP), which is one of the moving particle methods, to 3D motion of liquid sloshing processes measured in a series of experiments. In the first part of this study, a typical sloshing experiment of single liquid phase is simulated to verify the present 3D FVP method for sloshing characteristics that include free surface behaviors. Second, simulations of sloshing problems with solid particles are performed to validate the applicability of the FVP method to the 3D motion of solid particle-liquid mixture flows. Some good agreements between the simulation and its corresponding experiment demonstrate applicability of the present FVP method to 3D fluid dynamics of liquid sloshing flow with solid particles.

Development and Elaboration of Numerical Method to Simulate Gas-Liquid-Solid Three-Phase Flows Based on MPS Method

2015 ◽  
Author(s):  
Ryohei Takahashi ◽  
Makoto Yamamoto
Keyword(s):  
Numerical Method ◽  
Great Influence ◽  
Grid Method ◽  
Physical Models ◽  
Particle Methods ◽  
Two Phase ◽  
Microscopic Scale ◽  
Mps Method ◽  
Three Phase ◽  
Three Phase Flow

In recent years, the utilization of computational fluid dynamics (CFD) in various industrial fields has broadened following developments in computer technology. Although mainstream CFD is currently based on a grid method in an Eulerian framework, it is difficult to apply this to the simulation of problems in which large deformations of interfaces between phases occur or where microscopic scale phenomena have a great influence on the entire flow field. For this reason, particle methods, which can offer advantages for dealing with interface deformations and microscopic scale phenomena, are now receiving attention. Among the various particle methods, the moving-particle semi-implicit (MPS) method [1] is the most well-established and various physical models and extended numerical methods have been developed using it. In this study, we developed a numerical method to simulate a gas-liquid-solid three-phase flow based on the MPS approach. This method makes possible the coupling of independent computations of different phases. We conducted numerical tests on gas-liquid two-phase, liquid-solid two-phase and gas-liquid-solid three-phase simulations. Computational targets are modelling the dam break and solid-particle impingement phenomena. The computational results indicate reasonable agreement with the experimental results. We confirmed that the present method can reproduce the interactions between gas, liquid and solid phases that are difficult to reproduce with conventional grid methods.

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