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

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.

2017 ◽  
Vol 66 ◽  
pp. 95-116 ◽  
Author(s):  
Farnoush A. Daneshvar ◽  
G. Reza Rakhshandehroo ◽  
Nasser Talebbeydokhti

Author(s):  
I. L. Collings

AbstractSolutions are found to two cusp-like free-surface flow problems involving the steady motion of an ideal fluid under the infinite-Froude-number approximation. The flow in each case is due to a submerged line source or sink, in the presence of a solid horizontal base.


2016 ◽  
Vol 13 (04) ◽  
pp. 1641018 ◽  
Author(s):  
Zhenyuan Tang ◽  
Youlin Zhang ◽  
Decheng Wan

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.


Author(s):  
Masahiro Kondo ◽  
Takahiro Fujiwara ◽  
Issei Masaie ◽  
Junichi Matsumoto

AbstractParticle methods for high-viscous free-surface flows are of great use to capture flow behaviors which are intermediate between solid and liquid. In general, it is important for numerical methods to satisfy the fundamental laws of physics such as the conservation laws of mass and momentum and the thermodynamic laws. Especially, the angular momentum conservation is necessary to calculate rotational motion of high-viscous objects. However, most of the particle methods do not satisfy the physical laws in their spatially discretized system. The angular momentum conservation law is broken mostly because of the viscosity models, which may result in physically strange behavior when high-viscous free-surface flow is calculated. In this study, a physically consistent particle method for high-viscous free-surface flows is developed. The present method was verified, and its performance was shown with calculating flow in a rotating circular pipe, high-viscous Taylor–Couette flow, and offset collision of a high-viscous object.


Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1349 ◽  
Author(s):  
Mohammad Amin Nabian ◽  
Leila Farhadi

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.


Author(s):  
Hocine Mekias ◽  
Jean-Marc Vanden-Broeck

AbstractTwo-dimensional free-surface flows produced by a submerged source in a fluid of infinite depth are considered. It is assumed that the point on the free surface just above the source is a stagnation point and that the fluid outside two shear layers is at rest. The free-surface profile and the shape of the shear layers are determined numerically by using a series-truncation method. It is shown that there is a solution for each value of the Froude number F > 0. When F tends to infinity, the flow also describes a thin jet impinging in a fluid at rest.


Author(s):  
Arthur E. P. Veldman ◽  
Henk Seubers ◽  
Peter van der Plas ◽  
Joop Helder

The simulation of free-surface flow around moored or floating objects faces a series of challenges, concerning the flow modelling and the numerical solution method. One of the challenges is the simulation of objects whose dynamics is determined by a two-way interaction with the incoming waves. The ‘traditional’ way of numerically coupling the flow dynamics with the dynamics of a floating object becomes unstable (or requires severe underrelaxation) when the added mass is larger than the mass of the object. To deal with this two-way interaction, a more simultaneous type of numerical coupling is being developed. The paper will focus on this issue. To demonstrate the quasi-simultaneous method, a number of simulation results for engineering applications from the offshore industry will be presented, such as the motion of a moored TLP platform in extreme waves, and a free-fall life boat dropping into wavy water.


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