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.

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.

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.

A Comparison Between Weakly-Compressible Smoothed Particle Hydrodynamics (WCSPH) and Moving Particle Semi-Implicit (MPS) Methods for 3D Dam-Break Flows

2021 ◽  
pp. 2050036
Author(s):  
Rubens A. Amaro Junior ◽  
Liang-Yee Cheng ◽  
Sergei K. Buruchenko
Keyword(s):  
Free Surface ◽  
Surface Deformation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Dam Break ◽  
Weakly Compressible ◽  
Highly Nonlinear ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Moving Particle

Lagrangian particle-based methods have opened new perspectives for the investigation of complex problems with large free-surface deformation. Some well-known particle-based methods adopted to solve non-linear hydrodynamics problems are the smoothed parti- cle hydrodynamics (SPH) and the moving particle semi-implicit (MPS). Both methods model the continuum by a system of Lagrangian particles (points), but adopting distinct approaches for the numerical operators, pressure calculation, and boundary conditions. Despite the ability of the particle-based methods in modeling highly nonlinear hydrodynamics, some shortcomings, such as unstable pressure computation and high computational cost remain. In order to assess the performance of these two methods, the weakly-compressible SPH (WCSPH) parallel solver, DualSPHysics, and an in-house incompressible MPS solver are adopted in this work. Two test cases consisting of three-dimensional (3D) dam-break problems are simulated, and wave heights, pressures and forces are compared with the available experimental data. The influence of the artificial viscosity on the accuracy of WCSPH is investigated. Computational times of both solvers are also compared. Finally, the relative benefits of the methods for solving free-surface problems are discussed, therefore providing directions of their applicability.

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.

Local Study of Jet of a Fluid Sloshing Inside a Rolling Tank

2020 ◽  
Author(s):  
Wen-Huai Tsao ◽  
Spyros A. Kinnas
Keyword(s):  
Free Surface ◽  
High Speed ◽  
Fluid Velocity ◽  
Dynamic Responses ◽  
Surface Shape ◽  
Ansys Fluent ◽  
Local Study ◽  
Local Phenomenon ◽  
Fluid Sloshing ◽  
Stability And Accuracy

Abstract Sloshing is an important topic for the integrity of LNG tanks and the overall stability of the vessel. In the past, the interaction between the free surface and its substructure have been studied, especially where high-speed fluid jets impinge on the interior surface of the tank, and sometimes cause damage. In this paper, a boundary element method (BEM) with a fourth-order Runge-Kutta scheme is used to study the local phenomenon of nonlinear free-surface motion in a two-dimensional tank subject to roll motions. As the external excitations are nearly resonant with the fluid inside the tank, large free-surface deformations usually take place. The dynamic responses including the fluid velocity and pressure will grow drastically as the fluid is slamming on the walls. If no adequate conditions are applied, it is difficult to capture the peak physical quantities associated with strong nonlinear waves by most conventional Eulerian-Lagrangian methods. The numerical error will be accumulated and enlarged in just a few computational steps, which will eventually lead to unstable solutions. This paper will study the local phenomenon of a fast-moving jet forming on the wall of the tank, and its effect on the numerical stability and accuracy of the method overall. Some special numerical treatments are carried out for the local phenomenon approximation. The conservation of fluid mass is employed to obtain a reasonable geometry of the jet and its velocity along the wall. This provides a new set of rational boundary conditions applied on the walls, rather than using the artificial damping effect of other researchers. Results from the present method are compared with those from the volume of fluid (VOF) method implemented in ANSYS Fluent. The local free-surface shape in the vicinity of the jet and some local and global flow field patterns, including velocity and pressure, will be compared with and verified with experimental observations and measurements.

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.

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
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