Estimation of ship roll damping—A comparison of the decay and the harmonic excited roll motion technique for a post panamax container ship

Wassermann, Sven; Feder, Dag-Frederik; Abdel‐Maksoud, Moustafa

doi:10.1016/j.oceaneng.2016.02.009

Cited by 39 publications

(20 citation statements)

References 5 publications

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“…These tests can also be conducted through CFD simulations. Wassermann et al [10] estimated the roll damping of ships using CFD simulations of free decay and harmonic excited roll motion tests. They compared the advantages and disadvantages of both techniques.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Motion Performance of a Light Buoy Adopting Ecofriendly and Lightweight Materials in Waves

Jeong

Son

Lee

2020

JMSE

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In this study, the methods and results of numerical simulations to estimate the motion performance of a newly developed lightweight light buoy in waves and to check the effect of conceptually developed appendages on that performance were introduced. The results from a potential-based motion analysis with viscous damping coefficients obtained from free decay tests using computational fluid dynamics (CFD) and those obtained from wave motion simulation using CFD were compared. From these results, it was confirmed that viscous damping should be considered when the frequency of an incoming wave is close to the natural frequency of the buoy. It was estimated that the pitch and heave motions of the light buoy became smaller when the developed appendages were adopted. Although the quantitative superiority of the appendages was different, the qualitative superiority was similar between both results.

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Section: Introductionmentioning

confidence: 99%

Estimation of the Motion Performance of a Light Buoy Adopting Ecofriendly and Lightweight Materials in Waves

Jeong

Son

Lee

2020

JMSE

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show abstract

“…Using same method, Handschel and Maksoud [20] improved on Blumes work by reducing the measuring time, improving the estimation accuracy of roll damping coefficient over a wide frequency range and provided possibilities of determining roll damping with nonlinear stability moment curve. Wasserman et al [21] compared experimental and numerical results obtained from excited roll motion and free roll decay test and concluded that the excited roll motion was superior to the roll decay test for larger damping values.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the findings by Wasserman et al [21], free roll decay test is the most widely used method [5,[22][23][24][25][26][27] because it is the recommended technique by the International Maritime Organization (IMO) [28]. There are five methods to determine the damping coefficients for the vessel roll motion from roll decay test [29]: Quasi-linear method, Froude Energy method, Roberts Energy method, Averaging method and the Perturbation method.…”

Section: Introductionmentioning

confidence: 99%

Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Igbadumhe

Sallam

Fürth

et al. 2020

JMSE

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Wave excited roll motion poses danger for moored offshore vessels such as Floating Production Storage and Offloading (FPSO) because they cannot divert to avoid bad weather. Furthermore, slack cargo tanks are almost always present in FPSOs by design. These pose an increased risk of roll instability due to the presence of free surfaces. The most common method of determining roll damping is roll decay tests, yet very few test have been performed with liquid cargo, and most liquid cargo experiments use tanks that span the entire width of the vessel; which is seldom the case for full scale FPSO vessels during normal operations. This paper presents a series of roll decay test carried out on a FPSO model with two two-row-prismatic tanks with different filling levels. To directly investigate the coupling between the liquid sloshing and the vessel motion, without modifying the damping, tests were performed at a constant draft. The equivalent linear roll damping coefficients consisting of linear, quadratic and cubic damping terms are analyzed for each loading condition using four established methods, the Quasi-linear method, Froude Energy method, Averaging method and the Perturbation method. The results show that the cubic damping term is paramount for FPSOs and at low filling levels, were the FPSO is more damped. Recommendations regarding the applicability of the methods, their accuracy and computational effort is given and the effect of the liquid motion on the vessel motion is discussed.

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“…They found that the roll damping coefficient of the model without bilge keels is linear, however, with the bilge keels is strongly non-linear. Wassermann and Feder Wassermann, Feder [21] carried out model tests based on roll decay and HERM technique to calculate the roll damping of a container ship. They proposed various methods without additional filtering, curve fitting and offset manipulation of the recorded time series.…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of Roll Motion Characteristics and Damping Coefficient of a Ship

Kianejad

Lee

Liu

et al. 2018

JMSE

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Accurate calculation of the roll damping moment at resonance condition is essential for roll motion prediction. Because at the resonance condition, the moment of inertia counteracts restoring moment and only the damping moment resists increase in the roll angle. There are various methods to calculate the roll damping moment which are based on potential flow theory. These methods have limitations to taking into account the viscous effects in estimating the roll motion, while, CFD as a numerical method is capable of considering the viscous effects. In this study, a CFD method based on a harmonic excited roll motion (HERM) technique is used to compute the roll motion and the roll damping moment of a containership’s model in different conditions. The influence of excitation frequency, forward speed and degrees of freedom at beam-sea and oblique-sea realizations are considered in estimating the roll damping coefficients. The results are validated against model tests, where a good agreement is found.

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Estimation of ship roll damping—A comparison of the decay and the harmonic excited roll motion technique for a post panamax container ship

Cited by 39 publications

References 5 publications

Estimation of the Motion Performance of a Light Buoy Adopting Ecofriendly and Lightweight Materials in Waves

Estimation of the Motion Performance of a Light Buoy Adopting Ecofriendly and Lightweight Materials in Waves

Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Numerical Assessment of Roll Motion Characteristics and Damping Coefficient of a Ship

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