Dependence of Roll and Roll Rate in Nonlinear Ship Motions in Following and Stern Quartering Seas

AbstractA three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude-Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.

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Numerical analysis of ship motions for an offshore vessel

10.1063/5.0027329 ◽

2020 ◽

Author(s):

Sandita Pacuraru ◽

Florin Pacuraru ◽

Adham S. Bekhit

Keyword(s):

Numerical Analysis ◽

Ship Motions

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Ship Motions in Shallow Water

10.4043/2505-ms ◽

1976 ◽

Author(s):

Alan C. McClure ◽

R. Ray Nachlinger

Keyword(s):

Shallow Water ◽

Ship Motions

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Sea State Estimation Based on Ship Motions Measurements and Data Fusion

Volume 5: Ocean Engineering ◽

10.1115/omae2013-10657 ◽

2013 ◽

Author(s):

Céline Drouet ◽

Nicolas Cellier ◽

Jérémie Raymond ◽

Denis Martigny

Keyword(s):

Data Fusion ◽

State Estimation ◽

Wave Height ◽

Significant Wave Height ◽

Wave Spectrum ◽

Ocean Waves ◽

Ship Motions ◽

Sea State ◽

Significant Wave ◽

X Band

In-service monitoring can help to increase safety of ships especially regarding the fatigue assessment. For this purpose, it is compulsory to know the environmental conditions encountered: wind, but also the full directional wave spectrum. During the EU TULCS project, a full scale measurements campaign has been conducted onboard the CMA-CGM 13200 TEU container ship Rigoletto. She has been instrumented to measure deformation of the ship as well as the sea state encountered during its trip. This paper will focus on the sea state estimation. Three systems have been installed to estimate the sea state encountered by the Rigoletto: An X-band radar from Ocean Waves with WAMOS® system and two altimetric wave radars from RADAC®. Nevertheless, the measured significant wave height can be disturbed by several external elements like bow waves, sprays, sea surface ripples, etc… Furthermore, ship motions are also measured and can provide another estimation of the significant wave height using a specific algorithm developed by DCNS Research for the TULCS project. As all those estimations are inherently different, it is necessary to make a fusion of those data to provide a single estimation (“best estimate”) of the significant wave height. This paper will present the data fusion process developed for TULCS and show some first validation results.

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Heave Induced Internal Flow Fluctuations in Vertical Transport Systems for Deep Ocean Mining

Volume 8A: Ocean Engineering ◽

10.1115/omae2014-23684 ◽

2014 ◽

Author(s):

Stephan D. A. Hannot ◽

Jort M. van Wijk

Keyword(s):

Transport System ◽

Internal Flow ◽

Deep Ocean ◽

Vertical Transport ◽

Transport Systems ◽

Ship Motions ◽

Centrifugal Pumps ◽

Mining System ◽

Pump System ◽

Ocean Mining

Deep ocean mining systems will have to operate often in harsh weather conditions with heavy sea states. A typical mining system consists of a Mining Support Vessel (MSV) with a Vertical Transport System (VTS) attached to it. The transport system is a pump pipeline system using centrifugal pumps. The heave motions of the ship are transferred to the pump system due to the riser-ship coupling. Ship motions thus will have a significant influence on the internal flow in the VTS. In this paper, the influence of heave motions on the internal flow in the VTS for a typical mining system for Seafloor Massive Sulfide (SMS) deposits in Papua New Guinea is analyzed. Data on the wave climate in the PNG region is used to compute the ship motions of a coupled MSV-VTS. The ship motions then are translated into forces acting on the internal flow in order to compute fluctuations in the internal flow. In this way, the workability of the mining system with respect to the system’s production can be assessed. Based on a detailed analysis of the internal flow in relation to ship motions, the relevance of a coupled analysis for the design of VTS is made clear. This paper provides a method for performing such analyses.

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