• Structural Engineering and Mechanics
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• 제57권5호
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• pp.877-895
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• 2016

This paper is concerned with the analytical derivation of natural sloshing frequencies of liquid in annular cylindrical tank and its verification by experiment. The whole liquid domain is divided into three simple sub-regions, and the region-wise linearized velocity potentials are derived by the separation of variables. Two sets of matrix equations for solving the natural sloshing frequencies are derived by enforcing the boundary conditions and the continuity conditions at the interfaces between sub-regions. In addition, the natural sloshing frequencies are measured by experiment and the numerical accuracy of the proposed analytical method is verified through the comparison between the analytical and experimental results. It is confirmed that the present analytical method provides the fundamental sloshing frequencies which are in an excellent agreement with the experiment. As well, the effects of the tank radial gap, the bottom flow gap and the liquid fill height on the fundamental sloshing frequency are parametrically investigated.

• 한국해양공학회지
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• 제26권1호
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• pp.54-59
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• 2012

This study presents investigation on ullage effect in sloshing experiment. The experiment was done with two dimensional tank. Sloshing experiments were carried out in the tank with 6 different ullage pressures. The tested filling ratio was 30% of the tank height. The flow field was recorded with high speed camera. The sloshing impact pressure were measured at 18 locations. It was shown that the variation of ullage pressures influences the magnitude of pressure and flow field. This study demonstrated the importance of ullage pressure in sloshing test.

• 한국가시화정보학회지
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• 제17권3호
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• pp.39-45
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• 2019

A study on the sloshing flow of highly-viscous fluid in a rectangular box was made by both of theoretical approach and experimental visualization method. Assuming a smallness of external forcing to oscillate the container, it was investigated a linear sloshing flow of highly-viscous fluid utilizing asymptotic analysis by Taylor-series expansion as a small parameter R_e (≪1) in which R_e denotes Reynolds number. The theory predict that, during all cycles of sloshing, a linear shape of free surface will prevail in a bulk zone and it has confirmed in experiment. The relevance of perfect slip boundary condition, adopted in theoretical approach, to the bulk zone flow at the container wall was tested in experiment. It is found that quasi-steady coated thin film, which makes a lubricant layer between bulk flow and solid wall, is generated on the wall and the film makes a role to perfect slip boundary condition.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.331-343
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• 2013

The natural sloshing frequencies of annular cylindrical TLD are parametrically investigated by experiment, aiming at the exploration of its successful use for suppressing the structural vibration of spar-type floating wind turbine subject to multidirectional wind, wave and current excitations. Five prototypes of annular cylindrical TLD are defined according to the inner and outer radii of acryl container, and eight different liquid fill heights are experimented for each TLD prototype. The apparent masses near the first and second natural sloshing frequencies are parametrically investigated by measuring the apparent mass of interior liquid sloshing to the acceleration excitation. It is observed from the parametric experiments that the first natural sloshing frequency shows the remarkable change with respect to the liquid fill height for each TLD model with different container dimensions. On the other hand, the second natural sloshing frequency is not sensitive to the liquid fill height but to the gap size, for all the TLD models, convincing that the annular cylindrical sloshing damper can effectively suppress the wave- and wind-induced tilting motion of the spar-type floating wind turbine.

• 한국가시화정보학회지
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• 제18권3호
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• pp.14-22
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• 2020

An experiment, in the cases that satisfies deep water condition, has been performed to observe the strongly nonlinear sloshing flow in a rectangular tank. A variety of parametric study on oscillating frequency and amplitude was conducted and we found that two types of wave motions, sloshing wave and Faraday wave, could be persisting simultaneously even in horizontal sloshing problem. Moreover, it is observed both of symmetric and skewed symmetric Faraday wave exist. A comprehensive explanation is given to the generation mechanism of those waves and how to interact among them.

• 대한조선학회논문집
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• 제50권6호
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• pp.390-398
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• 2013

In this paper, an experimental study on sloshing problems in an independent B-type tank of STX Offshore and Shipbuilding Co. is described. Recently STX Offshore and Shipbuilding Co. introduced a new design of an independent B-type tank in order to reduce sloshing impact loads on LNG CCS. This tank has many internal members, so that sloshing flow and the resultant hydrodynamic loads are very different from those in typical membrane tanks. In this study, a series of sloshing experiment have been carried out for 1/50 scale model, and the main characteristics of sloshing load on the independent tank are observed. The properly scaled internal members such as swash bulkhead, center bulkhead and stringers have been installed in the test tank model, but sloshing pressures are measured on the tank walls only. The forced excitation signals have been generated by using the predicted ship motion in irregular sea states. The characteristics of sloshing loads on this tank have been observed in different filling levels with various heading angles, and sea states. In this paper, some key findings from the model tests 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.

• 한국소음진동공학회논문집
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• 제23권1호
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• pp.25-33
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• 2013

The floating offshore wind turbines are usually exposed to the wave and wind excitations which are irregular and undirected. In this paper, the sloshing characteristics of annular cylindrical tank were experimentally investigated to reduce the structural dynamic motion of floating offshore wind turbine which is robust to the irregular change of excitation direction of wind and wave. The formula for the natural sloshing frequencies of this annular cylindrical tank was derived theoretically. In order to validate this formula, the shaking equipment was established and frequency response functions were measured. Two types of tank were considered. The first and second natural sloshing frequencies were investigated according to the depth of the water. It has been observed that between theoretical and experimental results shows a good agreement.

• 한국해양공학회지
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• 제26권6호
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• pp.46-52
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• 2012

The motions and drift forces of side-by-side moored FSRU and LNGC including the sloshing effect, were studied using experiments. The FSRU and LNGC contained LNG cargo tanks and the LNG sloshing could affect the motions and drift forces of the structures due to its coupling with floating body motion. The effect of coupling can vary with the LNG filling level, and the effect of the filling level was investigated. The coupling effect was stronger at lower filling level. It was confirmed that longitudinal sloshing influenced the surge and surge mean drift force in head sea. In addition, gap flow affected the sway and mean drift forces. Sloshing attenuated the sway and yaw excited by gap flow in side-by-side configuration.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2009년도 춘계학술발표회
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• pp.85-86
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• 2009

슬로싱 현상은 탱크안의 자유표면을 갖는 유체의 비선형거동으로 탱크안의 구조물에 동적 하중을 발생시키므로 일반적으로 해양 구조물의 설계에 중요한 문제이다. 이 연구에서는 피칭운동을 하는 사각탱크 내에서 자유표면을 갖는 유체의 슬로싱에 대해 실험적으로 연구하였다.