scholarly journals Numerical Study of Parametric Roll on a Fishing Vessel

2013 ◽  
Author(s):  
Marilena Greco ◽  
Claudio Lugni
Keyword(s):  
Parametric Resonance ◽  
Numerical Study ◽  
Excitation Frequency ◽  
Forward Speed ◽  
Sea Waves ◽  
Fishing Vessel ◽  
Research Activity ◽  
Parametric Roll ◽  
Water On Deck ◽  
Incident Waves

Present research activity examines numerically the occurrence of parametric roll on a fishing vessel interacting with regular head-sea waves. The adopted solver is an efficient 3-D numerical Domain-Decomposition strategy for the seakeeping of a 6-dof vessel without and with small forward speed and possibly subjected to bottom-slamming and water-on-deck events. Here, the vessel has been assumed at rest and the excitation frequency is varied in the first parametric resonance zone and occurrence and features of the instability are examined in terms of nonlinearities of the incident waves and roll natural-to-incident wave frequency ratio. The analysis is performed both fully within the potential-flow theory and examining the effect on the parametric resonance of the viscous correction to the roll damping obtained from free-decay 3D model tests on the same ship. A system of four cables, horizontal in the mean configuration, will be used experimentally to limit the horizontal vessel motions. Here the numerical solver is used to analyze the influence of cable stiffness and of cable configuration on the vessel behavior and to help the design of the physical set up. The vessel has deep draft and high mean freeboard, these aspects work against the occurrence of bottom slamming and water-on-deck events. Without forward speed, no bottom slamming phenomena were observed while limited number of water-on-deck events with small amount of shipped liquid was recorded for the highest-frequency incident waves with largest steepnesses, among those causing parametric roll.

Parametric Resonance of a Fishing Vessel With and Without Anti-Roll Tank: An Experimental and Numerical Study

2017 ◽  
Author(s):  
Isar Ghamari ◽  
Odd M. Faltinsen ◽  
Marilena Greco ◽  
Claudio Lugni
Keyword(s):  
Parametric Resonance ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Internal Flow ◽  
Mooring Line ◽  
Sea Waves ◽  
Fishing Vessel ◽  
Nonlinear Method ◽  
Line System ◽  
Fishing Vessels

Parametric resonance (PR) in roll is of concern for fishing vessels, especially in head-sea waves. Here the effect of passive anti-roll free-surface tank is investigated experimentally and numerically on realistic fishing-vessel geometry at zero forward speed. On the numerical side, the onboard tank is simulated using an open source computational fluid dynamic (CFD) development platform, OpenFOAM (Open Field Operation and Manipulation). The internal flow solver is coupled with the seakeeping solver, which is based on the weakly nonlinear method proposed in [1]. Experimentally, two different relevant scenarios were examined: 1) a 2D rectangular tank with shallow-water filling depth was forced to oscillate in roll and the loads induced on the tank were measured; 2) a fishing vessel was tested in a towing tank, prescribing regular head-sea waves. The vessel was examined both without and with anti-roll tanks and a mooring-line system was designed so to control the horizontal motions with limited effect on the parametric occurrence. The experiments on the fishing vessel are considered to assess the seakeeping solver. Both model tests and numerical results confirmed the effectiveness of an on-board tank in avoiding PR. For the examined cases with tank, the parametric resonance did not occur without forcing an initial roll. Moreover, the initial roll amplitude and roll phase relative to the heave motion matter for triggering the instability.

scholarly journals Numerical Study of Bilge-Keel Effect on Parametric Roll and Water on Deck for an FPSO

2015 ◽  
Author(s):  
Marilena Greco ◽  
Claudio Lugni ◽  
Giuseppina Colicchio ◽  
Odd M. Faltinsen
Keyword(s):  
Numerical Study ◽  
Mooring Line ◽  
Mooring System ◽  
Regular Waves ◽  
Research Activity ◽  
Parametric Roll ◽  
Line System ◽  
Operational Conditions ◽  
Water On Deck ◽  
Bilge Keel

This research activity represents the logical continuation of the work documented in [1] and [2] on water on deck and parametric roll for an FPSO in regular waves. Here the same numerical method, based on a domain-decomposition strategy, is used to examine the platform with bilge keels, both without and with mooring-line system. It is found that bilge keels with length 40% of the ship length and with breadth the 3% of the ship breadth limit effectively the roll when instability is promoted by vertical bow motions in waves. In these conditions also the amount of the shipped water is substantially reduced. Large roll induced by the coupling with the lateral motions seems to be less well counteracted and remains close to 10° for steepness kA ≥ 0.2. This value is often set as maximum allowed amplitude for FPSOs in normal operational conditions. Also the effect on the shipped water is limited in this case. Increasing the bilge-keels breadth is confirmed to be beneficial but the combination of the mooring system with dynamic positioning appears needed for a proper control of the roll motion in the worst examined cases.

scholarly journals Investigation of Parametric Resonance in Roll for Container Carrier Ships

2015 ◽  
Author(s):  
Isar Ghamari ◽  
Odd M. Faltinsen ◽  
Marilena Greco
Keyword(s):  
Parametric Resonance ◽  
Potential Flow ◽  
Present Method ◽  
Design Stage ◽  
Sea Waves ◽  
Parametric Roll ◽  
Fishing Vessels ◽  
Strip Theory ◽  
Parametric Roll Resonance ◽  
2D And 3D

Parametric roll resonance is of concern for container and fishing vessels, especially in head-sea waves. Here this phenomenon is investigated with a numerical method based on potential-flow theory with viscous corrections for the roll damping. The seakeeping problem is handled by considering a strip theory and assuming a 5-DOF system. Nonlinearities are accounted for in the Froude-Krylov and hydrostatic loads. The solver has been validated against experiments on a C11 class container carrier ship in terms of parametric resonance occurrence and features for different ship forward speeds and headings, wavelengths, wave amplitudes and wave headings. The overall agreement is good but there are some discrepancies. For instance, the simulations show capsizing in some cases while it does not happen in the experiments. The results from present method can be used to generate 2D and 3D polar diagrams identifying the zones with parametric roll occurrence, and are very handy for masters aboard ships. This type of information is valuable at design stage and can be used aboard vessels for a safer voyage.

Numerical study of sea waves created by tropical cyclone Jelawat

2011 ◽  
Vol 30 (5) ◽  
pp. 64-70 ◽  
Author(s):  
Jie Li ◽  
Hongbao Qian ◽  
hai Li ◽  
Yu Liu ◽  
Zhiyi Gao
Keyword(s):  
Tropical Cyclone ◽  
Numerical Study ◽  
Sea Waves

Research Opportunities Identified During the Casualty Analysis of the Fishing Vessel Arctic Rose

2003 ◽  
Vol 40 (04) ◽  
pp. 270-277
Author(s):  
George A. Borlase
Keyword(s):  
Research Community ◽  
Coast Guard ◽  
Fishing Vessel ◽  
Water On Deck ◽  
Interior Spaces ◽  
Static And Dynamic Stability ◽  
Broad Variety ◽  
Stability Issues ◽  
Marine Safety ◽  
The U.S

During the course of the U.S. Coast Guard Marine Safety Center's analysis of the sinking of the fishing vessel Arctic Rose, a broad variety of stability issues were encountered that have not yet been addressed in the research community. The effect of freeboard on static and dynamic stability needs to be studied to ensure minimum reserve buoyancy and limit the effects of water on deck. The area of flooding stability, where a vessel's displacement, centers of gravity, and stability characteristics are constantly changing due to progressive flooding, needs to be further investigated. Time-domain analyses of progressive flooding in a seaway are needed, as are model tests of progressive flooding from the weather deck into interior spaces of a vessel. Additionally, a better understanding is needed of the behavior of the vessel between when the vessel capsizes due to loss of righting arm and sinks because flooding weight exceeds reserve buoyancy, and the attitude of a vessel as it falls through the water column to the ocean floor.

Numerical simulation of a fishing vessel in parametric roll in head seas

2006 ◽  
Vol 2 (1-2) ◽  
pp. 39-44
Author(s):  
Dimitris Spanos ◽  
Apostolos Papanikolaou
Keyword(s):  
Numerical Simulation ◽  
Fishing Vessel ◽  
Parametric Roll
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