Assessment of Ship Roll Damping Through Full Scale and Model Scale Experiments and Semi-empirical Methods

Söder, Carl-Johan; Rosén, Anders; Werner, Sofia; Huss, Mikael; Kuttenkeuler, Jakob

doi:10.1007/978-3-030-00516-0_10

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…It was shown by Kawahara et al ( 2011) that Ikeda's method does not work for some modern ships with buttock flow sterns. Söder et al (2019b) also showed that Ikeda's method was not capable of accurately predicting the roll damping for a Pure Car and Truck Carrier. The SI-method being a simplified version of Ikeda's method most likely inherits its problems but also introduces some extrapolation errors as reported by Rudakovié (2017).…”

Section: Accuracy Of Current Methods For Predicting Roll Dampingmentioning

confidence: 99%

“…Two different solution approaches have been investigated for the system identification, i.e. the 'derivation approach' (referred to as PIT in IMO 2006) and the 'integration approach' which is similar to what Söder et al (2019b) used. In the derivation approach, the first and second roll time derivatives are calculated numerically so that the parameters in the models are the only unknowns, and the optimal parameters that give the best fit can simply be determined using a least square fit.…”

Section: Estimation Of Roll Damping From Roll Decay Testsmentioning

confidence: 99%

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Analysis of roll damping model scale data

Alexandersson

Mao

Ringsberg

2021

Ships and Offshore Structures

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Having an accurate prediction of ship roll damping is crucial when analysing roll motions. In this paper, the simplified Ikeda method (SI-method) is compared with the original Ikeda method. The methods are compared using results from a database of roll decay tests carried out on modern merchant ships and a smaller set of predictions in which the original Ikeda method was used. It was found that most of the ships in the database had dimensions outside the limits of the SI-method. Thus, the SI-method showed poor agreement with model tests outside its limits but acceptable agreement for ships within limits. It was found that the deviations were caused by extrapolation errors of the wave-damping in the SI-method. Two ways to improve the accuracy of the SI-method were proposed based on regression, which gave about the same accuracy as the original Ikeda method.

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Section: Accuracy Of Current Methods For Predicting Roll Dampingmentioning

confidence: 99%

Section: Estimation Of Roll Damping From Roll Decay Testsmentioning

confidence: 99%

Analysis of roll damping model scale data

Alexandersson

Mao

Ringsberg

2021

Ships and Offshore Structures

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“…One drawback of this study was that the full-scale numerical results were not validated against sea trial data. In a study by Carl-Johan Söder et al [5], it was shown through model-scale and full-scale experiments that the full-scale damping was slightly higher than in the model tests, and that this should be further investigated. The studies described above confirm that the accurate simulation of roll motion using CFD is necessary in order to investigate scale effects, as this method is not limited by the size of the object, although the results need to be validated to ensure reliability.…”

Section: Introductionmentioning

confidence: 94%

Investigation of the Scale Effects on Roll Motion for The Ship Bettica Using Numerical Simulation

Phuong,

Yoshida,

Taniguchi

et al. 2024

Polish Maritime Research

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In this paper, we focus on analysing scale effects on the roll motion of the Italian ship Bettica using a numerical method. First, the roll decay motion of the ship is simulated at both the model scale and full scale, and the predicted results are compared with experimental data to validate the numerical strategy. The results show that there are scale effects that cause the difference in roll amplitudes between the model and the full-scale ship. To investigate the viscous effects on the roll damping components, forced roll simulations are carried out at the model scale and full scale, and the roll damping components (frictional, wave-making, eddy-making, bilge keel and lift components) are obtained. An analysis of these roll damping components indicates that the frictional component is influenced by scale effects, especially in the case of zero or low forward speed. We also show that the bilge keel component is affected by scale effects when the height of the bilge keels is reduced to a certain value below the boundary layer thickness. The velocity fields around the bilge keels are analysed to better understand the scale effects.

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“…The hydrodynamic coefficients of the ship strongly influence the roll motion: inertia moment, damping moment, restoring moment, and excitation moment [20]. The roll motion coefficients are obtainable using numerical calculations and roll decay experiments in the laboratory [21] [22]. The procedure for obtaining accurate hydrodynamic coefficients is with the roll decay experiment contained in the manual ITTC 7.5-02-07-04.1 [23].…”

Section: Introductionmentioning

confidence: 99%

Roll dynamic coefficients approach of decay test using the Generalized Reduced Gradient method (GRG)

2023

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Sea transportation is the vehicle which dominant and vital in the world. The increasing number of ships, types, and uncertain climate change have caused many ship accidents that have caused loss of life and property. The International Maritime Organization (IMO) issued the latest regulation on the second generation of ship stability criteria based on the dynamic of ship roll motions. The survival of dynamic stability depends on the hydrodynamic coefficients, which numerical and experimental calculations can obtain. The problem is finding the hydrodynamic coefficients of the ship roll quickly and accurately from the experimental roll decay data. This paper uses the Generalized Reduced Gradient (GRG) optimization to find the roll motion coefficient with the objective function of a standard deviation. The results show that the roll decay experiment graph is close optimization for variations of the minimum standard deviation used: all data, maximum-minimum amplitude, maximum amplitude, and minimum amplitude. The most similar chart to the experiment is optimization using a standard deviation of maximum-minimum amplitude with the optimal objective function σ = 1.006776 closest σ=1; obtained variable 0.1087688 m; 3.00306E-05 m-ton-sec. Based on sensitivity tests for various scenarios, optimization with a standard deviation of maximum amplitude has a high sensitivity, so it is necessary to avoid or be careful in its use. Generally, the GRG optimization method has the advantage of finding the hydrodynamic roll coefficient quickly and accurately.

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Assessment of Ship Roll Damping Through Full Scale and Model Scale Experiments and Semi-empirical Methods

Cited by 6 publications

References 5 publications

Analysis of roll damping model scale data

Analysis of roll damping model scale data

Investigation of the Scale Effects on Roll Motion for The Ship Bettica Using Numerical Simulation

Roll dynamic coefficients approach of decay test using the Generalized Reduced Gradient method (GRG)

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