[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This paper assesses some recent trends in the novel numerical meshless method smoothed particle hydrodynamics, with particular focus on its potential use in modelling free-surface flows. Due to its Lagrangian nature, smoothed particle hydrodynamics (SPH) appears to be effective in solving diverse fluid-dynamic problems with highly nonlinear deformation such as wave breaking and impact, multi-phase mixing processes, jet impact, sloshing, flooding and tsunami inundation, and fluid–structure interactions. The paper considers the key areas of rapid progress and development, including the numerical formulations, SPH operators, remedies to problems within the classical formulations, novel methodologies to improve the stability and robustness of the method, boundary conditions, multi-fluid approaches, particle adaptivity, and hardware acceleration. The key ongoing challenges in SPH that must be addressed by academic research and industrial users are identified and discussed. Finally, a roadmap is propose...

Smoothed particle hydrodynamics (SPH) for free-surface flows: past, present and future

Smoothed particle hydrodynamics method for fluid flows, towards industrial applications: Motivations, current state, and challenges

Comparative study on accuracy and conservation properties of two particle regularization schemes and proposal of an optimized particle shifting scheme in ISPH context

The article aims at providing an up-to-date review on several latest advancements related to particle methods with applications in coastal and ocean engineering. The latest advancements corresponding to accuracy, stability, conservation properties, multiphase multi-physics multi-scale simulations, fluid-structure interactions, exclusive coastal/ocean engineering applications and computational efficiency are reviewed. The future perspectives for further enhancement of applicability and reliability of particle methods for coastal/ocean engineering applications are also highlighted.

/pdf/on-the-state-of-the-art-of-particle-methods-for-coastal-and-4emfnigqnn.pdf

On the state-of-the-art of particle methods for coastal and ocean engineering

Smoothed particle hydrodynamics (SPH) method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. The splitting algorithm is that, when a coarse (mother) particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process, conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. Finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.

Application of particle splitting method for both hydrostatic and hydrodynamic cases in SPH

Numerical investigation of ice breaking by a high-pressure bubble based on a coupled BEM-PD model

A process of underwater explosion of a charge near a rigid wall includes three main stages: charge detonation, bubble pulsation
and jet formation. A smoothed particle hydrodynamics (SPH) method has natural advantages in solving problems with large
deformations and is suitable for simulation of processes of charge detonation and jet formation. On the other hand, a boundary
element method (BEM) is highly efficient for modelling of the bubble pulsation process. In this paper, a hybrid algorithm, fully
utilizing advantages of both SPH and BEM, was applied to simulate the entire process of free and near-field underwater
explosions. First, a numerical model of the free-field underwater explosion was developed, and the entire explosion process–
from the charge detonation to the jet formation–was analysed. Second, the obtained numerical results were compared with the
original experimental data in order to verify the validity of the presented method. Third, a SPH model of underwater explosion
for a column charge near a rigid wall was developed to simulate the detonation process. The results for propagation of a shock
wave are in good accordance with the physical observations. After that, the SPH results were employed as initial conditions for
the BEM to simulate the bubble pulsation. The obtained numerical results show that the bubble expanded at first and then shrunk
due to a differences of pressure levels inside and outside it. Here, a good agreement between the numerical and experimental
results for the shapes, the maximum radius and the movement of the bubble proved the effectiveness of the developed numerical
model. Finally, the BEM results for a stage when an initial jet was formed were used as initial conditions for the SPH method to
simulate the process of jet formation and its impact on the rigid wall. The numerical results agreed well with the experimental
data, verifying the feasibility and suitability of the hybrid algorithm. Besides, the results show that, due to the effect of the
Bjerknes force, a jet with a high speed was formed that may cause local damage to underwater structures.

/pdf/sph-bem-simulation-of-underwater-explosion-and-bubble-3nzzudgojh.pdf

SPH-BEM simulation of underwater explosion and bubble dynamics near rigid wall

Numerical simulation on the whole process of an underwater explosion between a deformable seabed and a free surface

The dynamic buckling characteristics and criteria of a ship’s structural stiffened plate subjected to underwater explosion impact loads are investigated in this study. Using the structural deformations observed in the experiments of underwater explosions against a plated grillage model, the mode shapes of the dynamic buckling were obtained. Through the construction of a computational model of stiffened plates subjected to an underwater explosion shock wave, the impact load was theoretically calculated and transformed into a rectangular pulse. According to the different response patterns of stiffened plates under different impact loads, a dynamic buckling criterion for the stiffened plates subjected to an explosion shock wave was proposed. Additionally, the static buckling phenomenon in the stiffened plates was analysed based on the minimum excess principle. In combination with the dynamic buckling criterion, the effects of various stiffening configurations on the dynamic and static buckling loads are discussed. The calculation results show that when the equivalent rectangular pulse is 2–3 times that of the static buckling load, the responses of the stiffened plates under the original shock load and the equivalent rectangular pulse are virtually identical. The impact load amplitude is the primary influencing factor in the dynamic buckling of stiffened plates subjected to underwater explosive impact loads. The stiffened plate aspect ratio has a substantial influence on the dynamic load factor. The analytical method and results are presented, which can be used to design stiffened optimum hull structures to enhance the dynamic load carrying capacity to withstand underwater shock damage.

A-Man Zhang

Papers

Application of particle splitting method for both hydrostatic and hydrodynamic cases in SPH

Numerical investigation of ice breaking by a high-pressure bubble based on a coupled BEM-PD model

SPH-BEM simulation of underwater explosion and bubble dynamics near rigid wall

Numerical simulation on the whole process of an underwater explosion between a deformable seabed and a free surface

Dynamic buckling of stiffened plates subjected to explosion impact loads