• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.169-174
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• 2013

The computational fluid dynamics software FLUENT is used to calculate and compare the hydrodynamic performance of the propeller-rudder system of a 42-m trawler, which is installed with a ducted propeller. The effects of rudder on the hydrodynamic performance of the ducted propeller and the wake flow behind the propeller are firstly investigated. In addition, the different rudder angles are also considered to further study the performance of this system.

• Wind and Structures
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• 제36권1호
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• pp.31-40
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• 2023

This paper investigates the mechanical behavior of full-scale offshore fish cages under hydrodynamic loads. To simulate different cases, different materials were used in the fish cage and analyzed under different flow velocities. The cage system is studied in two parts: net cage and floating collar. Analyses were performed with the ANSYS Workbench program, which allows the Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) method to be used together. Firstly, the fish cage was designed, and adjusted for FSI: Fluid (Fluent) analysis. Secondly, mesh structures were created, and hydrodynamic loads acting on the cage elements were calculated. Finally, the hydrodynamic loads were transferred to the mechanical model and applied as a pressure on the geometry. In this study, the equivalent (von Mises) stress, equivalent strain, and total deformation values of cage elements under hydrodynamic loads were investigated. The data obtained from the analyses were presented as figures and tables. As a result, it has been shown that it is appropriate to use all the materials examined for the net cage and the floating collar.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.49-55
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• 2004

제한수역에서 선박조종시 선박간에 생기는 상호간섭력과 또한 이러한 선박들이 측벽으로부터 받는 간섭력은 항로설계 및 선박조종운동의 관점에서 보았을 때 대단히 중요한 문제이다. 이 논문에서는 측벽 부근을 항해하는 두 척의 대형선박에 미치는 측 벽의 간섭 영향에 대해서 다루었다. 이 논문의 목적은 협수로나 천수로와 같은 제한수로에서 근접하여 항해하는 선박들이 안전조종 운동을 할 수 있도록 상호 간섭력을 최소화 할 수 있는 선박의 속력 및 선박과 선박 및 측벽 상호간의 거리에 대한 계산을 행하고, 제한된 항로에서 안전하게 항해할 수 있는 기준을 마련하는데 있다.

• 한국항해항만학회지
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• 제29권1호
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• pp.17-22
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• 2005

제한수역에서 선박조종시 선박간에 생기는 상호간섭력과 또한 이러한 선박들이 측벽으로부터 받는 간섭력은 항로설계 및 선박조종 운동의 관점에서 보았을 때 대단히 중요한 문제이다. 이 논문에서는 측벽 부근을 항해하는 두 척의 대형선박에 미치는 측벽의 간섭 영향에 대해서 다루었다. 이 논문의 목적은 협수로나 천수로와 같은 제한수로에서 근접하여 항해하는 선박들이 안전조종운동을 할 수 있도록 상호 간섭력을 최소화 할 수 있는 선박의 속력 및 선박과 선박 및 측벽 상호간의 거리에 대한 계산을 행하고, 제한된 항로에서 안전하게 항해할 수 있는 기준을 마련하는데 있다.

• Korea-Australia Rheology Journal
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• 제13권3호
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• pp.141-148
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• 2001

In this research, experimental studies leave been performed on the hydrodynamic interaction between a spherical particle and a plane wall by measuring the force between the particle and wall. To approach the system as a resistance problem, a servo-driving system was set-up by assembling a microstepping motor, a ball screw and a linear motion guide for the particle motion. Glycerin and dilute solution of polyacrylamide in glycerin were used as Newtonian and non-Newtonian fluids, respectively. The polymer solution behaves like a Boger fluid when the concentration is 1,000 ppm or less. The experimental results were compared with the asymptotic solution of Stokes equation. The result shows that fluid inertia plays all important role in the particle-wall interaction in Newtonian fluid. This implies that the motion of two particles in suspension is not reversible even in Newtonian fluid. In non-Newtonian fluid, normal stress difference and viscoelasticity play important roles as expected. In the dilute solution weak shear thinning and the migration of polymer molecules in the inhomogeneous flow field also affect the physic of the problem.

• 한국지진공학회논문집
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• 제22권3호
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• pp.139-147
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• 2018

In the present study, effective hydrodynamic pressure modeling methods for three-dimensional earthquake safety analysis of a dam intake tower structure are investigated. Time history analysis results using the Westergaard added mass and Chopra added mass methods are compared with the one by the CASI (Coupled Acoustic Structural Interaction) method, which is accepted as giving almost exact solutions, to evaluate the difference in displacement response, stress and dynamic eccentricity. The 3D time history analysis of a realistic intake tower, which has the standard geometry widely used in Korea, shows that the Chopra added mass method gives similar results in displacement and stress and less conservative results in dynamic eccentricity to CASI ones, while the Westergaard added mass yields much more conservative results in all measures. This study suggests to use the CASI method directly for three-dimensional earthquake safety analysis of a dam intake tower, if computationally possible.

• 한국지진공학회논문집
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• 제19권4호
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• pp.145-159
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• 2015

A seismic response analysis method for three-dimensional floating offshore structures due to seaquakes is developed. The hydrodynamic pressure exerted on the structure is calculated taking into account the compressibility of the sea water, the fluid-structure interaction, the energy absorption by the seabed, and the energy radiation into infinity. To validate developed method, the hydrodynamic pressure induced by the vibration of a floating massless rigid circular disk is calculated and compared with an exact analytical solution. The developed method is applied to seismic analysis of a support structure for a floating offshore wind turbine subjected to the hydrodynamic pressures induced from a seaquake. Analysis results show that earthquake response of a floating offshore structure can be greatly influenced by the compressibility of fluid, the depth (natural frequencies) of the fluid domain, and the energy absorption capacity of the seabed.

• Journal of Ship and Ocean Technology
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• 제6권3호
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• pp.13-25
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• 2002

In this paper, the motion responses with hydrodynamic interaction effect between two off-shore floating structures in various heading waves are studied by using a linearized three-dimensional potential theory. Numerical calculations using three-dimensional pulsating source distribution techniques have been carried out for twelve coupled linear motion responses and relative motions of the barge and the ship in oblique waves. The computational results give a good correlation with the experimental results and also with other numerical results. As a result, the present computational tool can be used effectively to predict the motion responses of multiple offshore floating structures in waves.

• 한국안전학회지
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• 제18권1호
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• pp.101-107
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• 2003

Dynamic behavior of flexible rectangular liquid storage structures is analysed by the developed method. The rectangular liquid storage structures are assumed to be fixed to the ground and a moving coordinate system is used. The irrotational motion of invicid and incompressible ideal fluid is represented by two analytic solutions. One is the solution of the fluid motion in the rigid rectangular liquid storage structure due to ground motions and the other is the solution of the fluid motion by the motion of the wall in the flexible rectangular liquid storage structure. The motion of structure is modeled by finite elements. The fluid-structure interaction effect is reflected into the coupled equation of motion as added fluid mass matrix. The free surface sloshing motion and hydrodynamic pressure acting on the wall in the flexible rectangular liquid storage structure due to the horizontal ground motion are obtained by the developed method and verified.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.43-56
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• 1998

A barge-type structure has been recently watched since The Floating Structures Association of Japan proposed the new concept as the most suitable one of floating airports. In this paper, the method, which is based on a combination of a three-dimensional source distribution method and the wave interaction theory is applied to very large floating structure of barge-type. The calculated results show good agreement with the experimental and calculated ones by Yago and remarkable characteristics concerning the hydroelastic behavior of the very large floating structure on the effects of hydrodynamic interactions and choice of body modelling.