scholarly journals Moving particle semi-implicit method with improved pressures stability properties

2017 ◽  
Vol 20 (6) ◽  
pp. 1268-1285 ◽  
Author(s):  
Masoud Arami Fadafan ◽  
Masoud-Reza Hessami Kermani
Keyword(s):  
Free Surface ◽  
Kernel Functions ◽  
Original Form ◽  
Test Case ◽  
Mps Method ◽  
Time Flow ◽  
Dummy Particles ◽  
Moving Particle ◽  
The Stability ◽  
Definition Of

Abstract Moving particle semi-implicit (MPS) method is one of the Lagrangian methods widely used in engineering issues. This method, however, suffers from unphysical oscillations in its original form. In the present study, a modified incompressible MPS method is proposed to suppress these oscillations and is used for simulating free surface problems. To demonstrate the stability of the presented method, different kernel functions are used in the case of numerical dam break modeling as a benchmark simulation. A simple form of definition of curved wall boundaries is suggested which eliminates dummy particles and subsequently saves CPU time. Flow over an ogee spillway is simulated for the first time with the I-MPS method and as a new test case which has several curved lines in its geometry. The comparisons between theoretical solutions/experimental data and simulation results in terms of free surface and pressure show the accuracy of the method.

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.

Squeeze Film Flow Analysis Using Moving Particle Semi-Implicit Calculation

2012 ◽  
Author(s):  
Nobuyuki Hirooka ◽  
Elon J. Terrell
Keyword(s):  
Stokes Equations ◽  
Flow Analysis ◽  
Squeeze Film ◽  
Navier Stokes ◽  
Original Form ◽  
Particle Interactions ◽  
Navier Stokes Equations ◽  
Mps Method ◽  
Moving Particle ◽  
Film Flows

We have presented an application of the modified Moving Particle Semi-implicit (MPS) method for squeeze film flows. In addition to calculating the flow field of a squeeze film using the full Navier-Stokes equations, this method has the advantage of being meshless, which gives it the capability of analyzing dynamic and/or highly transient squeeze films by discretizing the domain as a series of particles and numerically analyzing inter-particle interactions. Although past literature has indicated the MPS method in its original form to be unstable in terms of its calculation of pressure, a modified algorithm was implemented to provide agreement between the numerical results and the analytical solutions.

R&D of the Next Generation Safety Analysis Methods for Fast Reactors With New Computational Science and Technology: 3 — Improvement of Basic Fluid Dynamics Models for the COMPASS Code

2008 ◽  
Author(s):  
Shuai Zhang ◽  
Koji Morita ◽  
Noriyuki Shirakawa ◽  
Yuichi Yamamoto
Keyword(s):  
Fluid Dynamics ◽  
Free Surface ◽  
Solution Algorithm ◽  
Pressure Solution ◽  
Next Generation ◽  
Fast Reactors ◽  
Mps Method ◽  
Basic Fluid ◽  
Moving Particle ◽  
Dynamics Models

A new next generation safety analysis code, COMPASS, is designed based on the moving particle semi-implicit (MPS) method to provide local information for various key phenomena in core disruptive accidents of sodium-cooled fast reactors. In FY2006, improvement of basic fluid dynamics models for the COMPASS code was carried out and verified with fundamental verification calculations. In order to improve the numerical stability of MPS simulations, a fully implicit pressure solution algorithm was introduced instead of the two-stage MAC algorithm originally applied by MPS. With a newly developed free surface model, numerical difficulty caused by poor pressure solutions is overcome by involving free surface particles in the pressure Poisson equation. An improved algorithm was also proposed for surface tension calculation with the continuous surface force (CSF) model applied to the moving particle method. This algorithm provides higher numerical precision with the CSF model by interpolation between moving particles and background mesh. Application of the fully Lagrangian MPS method to solid-fluid mixture flow problems is straightforward. In FY2006, applicability of the MPS method to interactions between fluid and multi-solid bodies was investigated in comparison with dam-break experiments with solid balls. It was found that a modified pressure solution algorithm makes simulation with the passively moving solid model stable numerically. Though characteristic behavior of solids was successfully reproduced by the present numerical simulations, the comparisons with the experimental results showed that interactions between solids and solid-wall should be modeled for more precise simulations. Therefore, the discrete element method will be considered in the next stage.

Multi-Resolution MPS Method for Free Surface Flows

2016 ◽  
Vol 13 (04) ◽  
pp. 1641018 ◽  
Author(s):  
Zhenyuan Tang ◽  
Youlin Zhang ◽  
Decheng Wan
Keyword(s):  
Free Surface ◽  
Pressure Field ◽  
Fine Particles ◽  
Free Surface Flows ◽  
Surface Flows ◽  
Mps Method ◽  
Time Simulation ◽  
Long Time ◽  
Moving Particle ◽  
Dam Breaking

A multi-resolution moving particle semi-implicit (MPS) method is applied into two-dimensional (2D) free surface flows based on our in-house particle solver MLParticle-SJTU in the present work. Considering the effect of different size particles, both the influence radiuses of two adjacent particles are replaced by the arithmetic mean of their interaction radiuses. Then the modifications for kernel function of differential operator models are derived, respectively. In order to validate the present multi-resolution MPS method, two cases are carried out. Firstly, a hydrostatic case is performed. The results show that the contour of pressure field by multi-resolution MPS is quite in agreement with that by single resolution MPS. Especially, the multi-resolution MPS can still provide a relative smooth pressure together with the single resolution MPS in the vicinity of the interface between the high resolution and low resolution particles. For a long time simulation, the kinetic energy of particles by multi-resolution MPS can decrease quickly to the same level as that of single resolution MPS. In addition, a 2D dam breaking flow is simulated and the multi-resolution case can run stably during the whole simulation. The pressure by the multi-resolution MPS is in agreement with experimental data together with single resolution MPS. The contour of pressure field by the former is also similar to that by the later. Finally, the simulation by multi-resolution MPS is as accurate as the traditional MPS with fine particles distributed in the whole domain and the corresponding CPU time can be reduced.

scholarly journals MR-WC-MPS: A Multi-Resolution WC-MPS Method for Simulation of Free-Surface Flows

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1349 ◽  
Author(s):  
Mohammad Amin Nabian ◽  
Leila Farhadi
Keyword(s):  
Free Surface ◽  
Free Surface Flows ◽  
Submarine Landslide ◽  
Particle Methods ◽  
Computational Time ◽  
Computational Domain ◽  
Surface Flows ◽  
Mps Method ◽  
Weakly Compressible ◽  
Moving Particle

A Multi-Resolution Weakly Compressible Moving-Particle Semi-Implicit (MR-WC-MPS) method is presented in this paper for simulation of free-surface flows. To reduce the computational costs, as with the multi-grid schemes used in mesh-based methods, there is also a need in particle methods to efficiently capture the characteristics of different flow regions with different levels of complexity in different spatial resolutions. The proposed MR-WC-MPS method allows the use of particles with different sizes in a computational domain, analogous to multi-resolution grid in grid-based methods. To evaluate the accuracy and efficiency of the proposed method, it is applied to the dam-break and submarine landslide tests. It is shown that the MR-WC-MPS results, while about 15% faster, are in good agreement with the conventional single-resolution MPS results and experimental results. The remarkable ability of the MR-WC-MPS method in providing robust savings in computational time for up to 60% is then shown by applying the method for simulation of extended submarine landslide test.

Improvement of Pressure Calculations in the Moving Particle Semi-Implicit Method for Free-Surface Flows

2019 ◽  
Vol 17 (09) ◽  
pp. 1950062 ◽  
Author(s):  
Wenjin Gou ◽  
Shuai Zhang ◽  
Yao Zheng
Keyword(s):  
Free Surface ◽  
Free Surface Flow ◽  
Free Surface Flows ◽  
Surface Flow ◽  
Surface Boundary ◽  
Navier Stokes Equation ◽  
Surface Flows ◽  
Mps Method ◽  
Flow Simulations ◽  
Moving Particle

In this paper, numerical improvements are implemented for solving for the pressure in the moving particle semi-implicit (MPS) method for free-surface flow simulations. The tensile instability problem is solved using a dynamic stabilization (DS) algorithm. The low numerical diffusion of this algorithm is shown through numerical tests. A free-surface treatment that includes an accurate free-surface particle detection algorithm and the implicit application of a free-surface boundary condition is used. The solution of the Navier–Stokes equation is improved using a particle shifting (PS) algorithm. The proposed MPS method for free-surface flow simulations is successfully applied in several benchmark tests and two- and three-dimensional dam break problems. The numerical simulation results agree well with the analytical and empirical ones. It is shown that the proposed MPS method effectively improves the stability and accuracy of simulations of free-surface flows.

Postmodern More

Moreana ◽  
2003 ◽  
Vol 40 (Number 153- (1-2) ◽  
pp. 219-239
Author(s):  
Anne Lake Prescott
Keyword(s):  
Human Language ◽  
Thomas More ◽  
The Stability ◽  
Definition Of ◽  
Recent Critic

Thomas More is often called a “humanist,” and rightly so if the word has its usual meaning in scholarship on the Renaissance. “Humanist” has by now acquired so many different and contradictory meanings, however, that it needs to be applied carefully to the likes of More. Many postmodernists tend to use the word, pejoratively, to mean someone who believes in an autonomous self, the stability of words, reason, and the possibility of determinable meanings. Without quite arguing that More was a postmodernist avant la lettre, this essay suggests that he was not a “humanist” who stalks the pages of much recent postmodernist theory and that in fact even while remaining a devout Catholic and sensible lawyer he was quite as aware as any recent critic of the slipperiness of human selves and human language. It is time that literary critics tightened up their definition of “humanist,” especially when writing about the Renaissance.

Elaborating a Software Package for Solving Free-surface Hydrodynamic Problems Based on the MPS Method

Vestnik MEI ◽  
2017 ◽  
pp. 13-19
Author(s):  
D. V. Gudemenko ◽  
◽  
P. S. Klimov ◽  
V. I. Melikhov ◽  
O. I. Melikhov ◽  
...  
Keyword(s):  
Free Surface ◽  
Software Package ◽  
Mps Method

scholarly journals Influence of study model, baseline catalytic concentrations and analytical system on the stability of serum alanine aminotransferase

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Josep Miquel Bauça ◽  
Andrea Caballero ◽  
Carolina Gómez ◽  
Débora Martínez-Espartosa ◽  
Isabel García del Pino ◽  
...  
Keyword(s):  
Alanine Aminotransferase ◽  
Experimental Models ◽  
Individual Variability ◽  
Serum Samples ◽  
Multicentric Study ◽  
Different Temperatures ◽  
The Stability ◽  
Analytical System ◽  
Definition Of ◽  
Analytical Platforms

AbstractObjectivesThe stability of the analytes most commonly used in routine clinical practice has been the subject of intensive research, with varying and even conflicting results. Such is the case of alanine aminotransferase (ALT). The purpose of this study was to determine the stability of serum ALT according to different variables.MethodsA multicentric study was conducted in eight laboratories using serum samples with known initial catalytic concentrations of ALT within four different ranges, namely: <50 U/L (<0.83 μkat/L), 50–200 U/L (0.83–3.33 μkat/L), 200–400 U/L (3.33–6.67 μkat/L) and >400 U/L (>6.67 μkat/L). Samples were stored for seven days at two different temperatures using four experimental models and four laboratory analytical platforms. The respective stability equations were calculated by linear regression. A multivariate model was used to assess the influence of different variables.ResultsCatalytic concentrations of ALT decreased gradually over time. Temperature (−4%/day at room temperature vs. −1%/day under refrigeration) and the analytical platform had a significant impact, with Architect (Abbott) showing the greatest instability. Initial catalytic concentrations of ALT only had a slight impact on stability, whereas the experimental model had no impact at all.ConclusionsThe constant decrease in serum ALT is reduced when refrigerated. Scarcely studied variables were found to have a significant impact on ALT stability. This observation, added to a considerable inter-individual variability, makes larger studies necessary for the definition of stability equations.

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