• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.922-925
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• 2011

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method widely used for the modeling fluid flows. Simulations of explosions require, besides the hydrodynamic equations, a realistic equation of state, an energy source term, and a set of chemical kinetic equations to follow the composition changes of the gas during the explosion. The performance of the hydrodynamic equations is investigated in the framework of the Sedov-Taylor blast-wave. The implementation of chemical kinetic equations and equation of state is studied with 1D detonation of TNT slab. Our results are compared to those from analytical and experimental studies.

• 한국가족관계학회지
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• 제23권2호
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• pp.67-87
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• 2018

Objectives: The purpose of this study is to critically review the recent discourse on single-person households (SPH) that appeared in Korean newspapers. Specifically, we analyzed articles in five major daily newspapers, which are representative of the media in Korean society, and examined the types of titles, subjects, and contents of articles in which SPH were mentioned. Method: For this purpose, 538 articles on SPH or "living alone" that appeared in the five major Korean newspapers during 2011-2017 were analyzed using content analysis methods. Results: Our analysis revealed eight major topics(living arrangement and household characteristics; financial instruments; food, clothing, and housing culture; policy; welfare; relationships; safety; values and attitudes). The results show that there is a surge of articles portraying neutral images of SPH in Korean newspapers, thereby emphasizing the recent growth in the number of SPH and the information relating to this population group. Although negative images of SPH continue to exist in the discourse, in recent times we found these attitudes to have become less prevalent compared to neutral images or even positive discourse. We also found that the discourse on these topics and arguments can be divided into four themes-the diversity of SPHs, the solo economy for single households, safety issues, and social relationships. Conclusions: Theoretical and policy implications on family studies relating to SPH are discussed.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.752-762
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• 2021

The Smoothed Particle Hydrodynamics is one of the most widely used mesh-free numerical method for thermo-fluid dynamics. Due to its Lagrangian nature and simplicity, it is recently gaining popularity in simulating complex physics with large deformations. In this study, the 3D single/two-phase numerical simulations are performed on the Liquid Metal Reactor (LMR) centralized sloshing benchmark experiment using the SPH parallelized using a GPU. In order to capture multi-phase flows with a large density ratio more effectively, the original SPH density and continuity equations are re-formulated in terms of the normalized-density. Based upon this approach, maximum sloshing height and arrival time in various experimental cases are calculated by using both single-phase and multi-phase SPH framework and the results are compared with the benchmark results. Overall, the results of SPH simulations show excellent agreement with all the benchmark experiments both in qualitative and quantitative manners. According to the sensitivity study of the particle-size, the prediction accuracy is gradually increasing with decreasing the particle-size leading to a higher resolution. In addition, it is found that the multi-phase SPH model considering both liquid and air provides a better prediction on the experimental results and the reality.

• Structural Engineering and Mechanics
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• 제14권4호
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• pp.455-472
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• 2002

The paper involves the study on the elastic and elasto-plastic stress wave propagation in the 1-D and 2-D solid media. The Smooth Particle Hydrodynamics equations governing the elastic and elasto-plastic large deformation dynamic response of solid structures are presented. The proposed additional stress points are introduced in the formulation to mitigate the tensile instability inherent in the SPH approach. Both incremental rate approach and leap-frog algorithm for time integration are introduced and the new solution algorithm is developed and implemented. Two examples on stress wave propagation in aluminium bar and 2-D elasto-plastic steel plate are included. Results from the proposed SPH approach are compared with available analytical values and finite element solutions. The comparison illustrates that the stress wave propagation problems can be effectively solved by the proposed SPH method. The study shows that the SPH simulation is a reliable and robust tool and can be used with confidence to treat transient dynamics such as linear and non-linear transient stress wave propagation problems.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3264-3274
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• 2021

In a severe accident of light water reactor (LWR), molten core material (corium) can be released into the wet cavity, and a fuel-coolant interaction (FCI) can occur. The molten jet with high speed is broken and fragmented into small debris, which may cause a steam explosion or a molten core concrete interaction (MCCI). Since the premixing stage where the jet breakup occurs has a large impact on the severe accident progression, the understanding and evaluation of the jet breakup phenomenon are highly important. Therefore, in this study, the jet breakup simulations were performed using the Smoothed Particle Hydrodynamics (SPH) method which is a particle-based Lagrangian numerical method. For the multi-fluid system, the normalized density approach and improved surface tension model (CSF) were applied to the in-house SPH code (single GPU-based SOPHIA code) to improve the calculation accuracy at the interface of fluids. The jet breakup simulations were conducted in two cases: (1) jet breakup without structures, and (2) jet breakup with structures (control rod guide tubes). The penetration depth of the jet and jet breakup length were compared with those of the reference experiments, and these SPH simulation results are qualitatively and quantitatively consistent with the experiments.

• International Journal of Ocean System Engineering
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• 제2권4호
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• pp.200-208
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• 2012

Surge overflow may cause damage on earthen levees. Levee strengthened on the levee crest and landward-side slope can provide protection against the erosion damage induced by surge overflow. In this paper, surge overflow of a roller compacted concrete RCC strengthened levee was studied in a purely Lagrangian and meshless approach, the smoothed particle hydrodynamics (SPH) method. After verifying the developed model with analytical solution and comparing the results with full-scale experimental data, the roughness and erosion parameters were calibrated. The water thickness, flow velocity, and erosion depth at crest, landward-side slope and toe were calculated. The characteristics of flow hydraulics and erosion on the RCC strengthened levee are given. The results indicate that the RCC strengthened levee can resist erosion damage for a long period.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.331-336
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• 2004

This paper is concerned with numerical simulation of hypervelocity impacts(HVIs) of a projectile on laminated composite plate targets using SPH method. A one-parameter visco-plasticity model and damage model is used to describe the HVIs response of composite materials. The numerical simulation was carried out for a steel projectile striking to aluminum plate targets and for an aluminum projectile striking to laminated graphite/epoxy (Gr/Ep) composite plate targets. Through the numerical simulation, comparison with the HVIs response of isotropic materials and composite materials is discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권2호
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• pp.122-125
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• 2011

In this work, the movement pattern of a floating breakwater is numerically analyzed using Smoothed Particle Hydrodynamic (SPH) method as a Lagrangian scheme. At the seaside, the regular incident waves with varying height and period were considered as the dynamic free surface boundary conditions. The smooth and impermeable beach slope was defined as the bottom boundary condition. The effects of various boundary conditions such as incident wave characteristics, beach slope, and water depth on the movement of the floating body were studied. The numerical results are in good agreement with the available experimental data in the literature The results of the movement of the floating body were used to determine the transmitted wave height at the corresponding boundary conditions.

• Smart Structures and Systems
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• 제15권2호
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• pp.299-314
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• 2015

Submersed rock-berm structures are frequently used for protection of underwater lifelines such as pipelines and power cables. During the service life, the rock-berm structure can experience several accidental loads such as anchor collision. The consequences can be severe with a certain level of frequency; hence, the structural responses should be carefully understood for implementing a proper structural health monitoring method. However, no study has been made to quantify the structural responses because it is hard to deal with the individual behavior of each rock. Therefore, this study presents a collision analysis of the submersed rock-berm structure using a finite element software package by facilitating the smoothed-particle hydrodynamics (SPH) method. The analysis results were compared with those obtained from the Lagrange method. Moreover, two types of anchors (stock anchor and stockless anchor), three collision points and two different drop velocities (terminal velocity of each anchor and 5 m/s) were selected to investigate the changes in the responses. Finally, the effect of these parameters (analysis method, anchor type, collision point and drop velocity) on the analysis results was studied. Accordingly, the effectiveness of the SPH method is verified, a safe rock-berm height (over 1 m) is proposed, and a gauge point (0.5 m above the seabed) is suggested for a structural health monitoring implementation.

• 대한조선학회논문집
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• 제47권4호
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• pp.525-532
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• 2010

In this paper, wave breakers which occur in two dimensional coasts are simulated using a SPH(Smoothed Particle Hydrodynamics) method which represents the movement of fluidic physical volume with particles. As continuative fluid is approximated to the particles, the simulations are performed using fully Lagrangian method without any grid system. Two-dimensional Navier-Stokes equations and continuity equation are used for the numerical simulations. To generate incident waves, a piston type wavemaker is employed. The accuracy of the wave which is numerically generated by the wavemaker is verified by comparing with analytical results. The computations are carried out with various wave heights and slopes. The wave patterns generated through the numerical simulations are compared with several existing experimental and computational results. Agreement between the experimental data and the computation results is comparatively good. Also, the breaker depth index and the breaker height index from the present calculations are compared with the existing experimental results, and the tendency is very similar.