• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.667-671
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• 2005

This study was carried out to examine the prediction of ship's manoeuvrability in initial design stage. New parameter representing basic hull form and stem shape were proposed. Captive model test were carried out to investigate the correlation coefficient between hydrodynamic coefficient and hull parameter. The results showed which parameter are positive correlation with hydrodynamic coefficient. Moreover correlation was examined between stem hull shape and ship's manoeuvrability. New empirical formulas for hydrodynamic coefficients were proposed These results can be used to predict a ship's manoeuvrability in initial design stage.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.1-13
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• 2001

RANS solver has been developed to solve the flows past a ship with a drift angle. The solver employs a finite volume method for the spatial discretization and Euler implicit method for the time integration. Turbulent flows are simulated by Spalart-Allmaras one-equation model. Developed solver is applied to analyze the hydrodynamic forces and flows of two tankers with a same forebody but different afterbodies. The computed flows and hydrodynamic forces are compared with the measured flows and captive model test data. The computed results show good agreements with experimental data and show clearly the effects of stern hull form on the hydrodynamic forces and the flows.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.65-79
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• 1994

In the present paper, An emphasis is laid upon effects of stern bulb on hydrodynamic property and manoeuvring performance. We carried out captive model tests in circulating water channel with two ship models of which the frame lines of aft bodies are different. such as normal stern form and stern form with bulb, but of which the other parts are exactly same. The tests conducted consist of hull resistance test, effective thrust measurement, oblique tow test, and measurements of factors related to rudder force. From the results of model tests, we discussed effects of stern bulb on hull forces and on hull-propeller-rudder interactions, comparing with normal stern form. Furthermore, we also discussed effects of stern bulb on course stability. turning ability. spiral characteristics and zig-zag manoeuvre by computer simulation. As a result, it is clarified that the adoption of stern bulb makes course stability the worse and turning ability the better. The difference of the hydrodynamic derivatives of naked hull between two ship forms cause the worse course stability of the ship with stern bulb. The differences of the effective inflow velocity to rudder and hull forces induced by steered rudder cause the better turning ability of the ship with stern bulb.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.90-101
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• 1992

Some practical methods have already been proposed for predicting the characteristics of ship manoeuvring motions at relatively high advance speed. However, these methods can hardly be applied to motions of ships in starting, stoppint, backing and slow steaming conditions, even though such extensive motions are of vital importance from a safety point of view particularly in harbour areas. The method presented here aims at predicting the characteristics of ship manoeuvring at low advance speed, which covers starting, stopping, backing and slow steaming conditions. The force mathematical models at large angles of incidence to the hull as well as under the tilde range of propeller operations are formulated. Simulations of various manoeuvres at low advance speed are carried out for two types of merchant ship, i.e. a LNGC and a VLCC. Comparisons between simulations and corresponding full-scale measurements or free-running model tests provide a first verification of the proposed mathematical models.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.151-151
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• 2023

An accurate prediction of the hydrodynamic maneuvering darivatives is essential to desing a robust control system of a UUV(unmanned underwater vehicle). Typically, these derivatives were estimated by either the towing tank experiment or semi-empirical methods. With the enhancement of high performance computing capacity, a numerical analysis using computational fluid dynamics has reach the level of experiment. Therefore, the aims of the present research are to numerically develop a computational model for the vertical planar motion mechanism of a UUV and to estimate the hydrodynamics loads in 6-DOF. The target structure of the present study was manta type UUV (12meter length). The numerical model was developed in 1/ 6 model scale. Numerical results were compared with the results of the towing tank experiment for validation. In the present study, a commercial RANS-based viscous solver STARCCM+ (ver 17.06) was used.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.369-376
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• 2019

Ship hydrodynamics in the confined waterways is challenging. When a ship is maneuvering in confined waterways, the hydrodynamic behavior may vary significantly because of the hydrodynamic interaction between the bottom of the ship hull and the seabed, or so-called shallow water effects. Thus, an accurate prediction of shallow water and bank effects is essential to minimizing the risk of the collision and the grounding of the ships. The hydrodynamic derivatives measured by the virtual captive model test provide a path to predicting the change in ship maneuverability. This paper presents a numerical simulation of captive model tests to predict the maneuverability of a ship in confined waterways. Also, straight and zig-zag simulation were conducted to predict the trajectory of a ship maneuvering in confined waterways. The results showed that the asymmetric flow around a ship induced by vicinity of banks causes pressure differences between the port and starboard sides and the trajectory of a ship maneuvering in confined waterways.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.735-740
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• 2010

This paper focuses on the effects of hydrodynamic forces between overtaking and overtaken vessels moving under the influences of external forces, such as strong wind and current in shallow water, in which condition the ship handling may become very complex. The purpose of this paper is to develop a guideline for safe conducting distance between two ships according to the velocity and the significance of external disturbances.

• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.340-345
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• 2017

It is important to predict the hydrodynamic maneuvering derivatives, which consist of the forces and moment acting on a hull during a maneuvering motion, when estimating the maneuverability of a ship. The estimation of the maneuverability of a ship with a change in the stern hull form is often performed at the initial design stage. In this situation, a method that can reflect the change in the hull form is necessary in the prediction of the maneuverability of the ship. In particular, the linear hydrodynamics maneuvering derivatives affect the yaw checking motion as the key factors. In the present study, static drift calculations were performed using Computational Fluid Dynamics (CFD) based on Reynolds Average Navier-Stokes (RANS) for a 40-segment hull. A prediction method for the linear hydrodynamic maneuvering derivatives was proposed using the slender body theory from the distribution of the lateral force acting on each segment of the hull. Moreover, the results of a comparison study to the model experiment for KVLCC1 performed by KRISO are presented in order to verify the accuracy of the static drift calculation. Finally, the linear hydrodynamic maneuvering derivatives obtained from both the model test and calculation are compared and presented to verity the usefulness of the method proposed in this study.

• Journal of Navigation and Port Research
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• v.37 no.4
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• pp.345-350
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• 2013

It is well known that the hydrodynamic forces and moments induced by the proximity of bank in confined waters, such as in a harbour or narrow channel affect ship's maneuvering motion. In this paper, the calculation method based on the slender body theory for estimation of the hydrodynamic force between ship and breakwater is applied, and also, the characteristic features of hydrodynamic force acting on a large vessel in the proximity of a breakwater are described and illustrated. Furthermore, the effects of water depth and the lateral spacing between ship and breakwater are summarized and discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.103-107
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• 2005

This study was carried out to examine the prediction of ship's manoeuvrability in initial design stage. New parameter representing basic hull form and stern shape were proposed. Captive model test were carried out to investigate the correlation coefficient between hydrodynamic coefficient and hull parameter. The results showed which parameter are positive correlation with hydrodynamic coefficient. Moreover correlation was examined between sternhull shape and ship's manoeuvrability. These results can be used to predict a ship's manoeuvrability in initial design stage.