A 3-d Rankine Source Seakeeping Method

Hamburg-Harburg, TU; Bertram, Volker

doi:10.1179/str.2009.56.2.002

Cited by 17 publications

(5 citation statements)

References 1 publication

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“…In other words, 4>° in Eq. [21][22][23]. < t>° is computed as described above; for small Froude numbers, typically below 0.15, a double-body approximation is usually used.…”

Section: Rankine Source Methods For Seakeepingmentioning

confidence: 99%

Rankine Source Method for Ship–Ship Interaction Problems

Graefe

Shigunov

Moctar

2015

Journal of Offshore Mechanics and Arctic Engineering

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A Rankine source method is extended and applied to ship-ship interaction problems. The method covers the nonlinear steady flow and linear seakeeping in the frequency domain. The nonlinear steady flow solution accounts fo r the nonlinear free-surface conditions, ship wave, and dynamic trim and sinkage. Periodic flow due to waves is linearized with respect to the wave amplitude, taking into account interactions with the nonlinear steady flow following Hachmann approach, which considers the steady perturbation potential as constant in the body-fixed reference frame. This is advantageous fo r the prediction o f ship motions at moderate to high Froude numbers. In this context, a new formulation o f the boundary condition fo r the multibody case is derived. Two examples are considered, overtaking in calm water and replenishment at sea. For a feeder vessel overtaken by a container ship, horizontal forces and yaw moment are computed and compared with ref erence data. As an example o f replenishment operation, interaction between a frigate and a supply vessel is studied. Ship motions are computed fo r two relative positions and three forward speeds and compared with model test data fo r the largest forward speed. The Rankine source method proves as more accurate compared with a zero-speed freesurface Green function method.

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“…In other words, 4>° in Eq. [21][22][23]. < t>° is computed as described above; for small Froude numbers, typically below 0.15, a double-body approximation is usually used.…”

Section: Rankine Source Methods For Seakeepingmentioning

confidence: 99%

Rankine Source Method for Ship–Ship Interaction Problems

Graefe

Shigunov

Moctar

2015

Journal of Offshore Mechanics and Arctic Engineering

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“…GL Rankine uses an empirical method to fulfil the radiation and open boundary condition [3,9]. On the side parts of the free sur face, a special boundary condition is used, which allows only wave propagating away from the ship.…”

Section: Rankine Panel Method Gl Rankinementioning

confidence: 99%

Linear and Nonlinear Sectional Loads With Potential and Field Methods

Graefe

Moctar

Oberhagemann

et al. 2014

Journal of Offshore Mechanics and Arctic Engineering

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A Rankine source method is applied to predict linear and weakly nonlinear sectional loads o f a modern container ship. The method uses solution in the frequency domain, lin earized with respect to wave amplitude about the nonlinear steady flow due to forward speed, which accounts for the nonlinear free-surf ace conditions, ship wave, and dynamic trim and sinkage. Weak nonlinearity of the sectional loads in waves (e.g., hogging sagging asymmetry) is taken into account by pressure extrapolation and integration up to the estimated actual water line. The sectional forces obtained with this method are com pared with the results of other methods, including (1) linear Rankine panel method, where flow due to waves is linearized about the double-body flow, (2) linear zero-speed Green function method with correction for forward speed, (3) fully nonlinear simulations based on field-based solution of Reynolds-averaged Navier-Stokes (RANS) equations, and (4) model tests. Comparison with RANS solution and model tests shows, that the pro posed method can accurately predict sectional loads for small to moderate wave heights.

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“…This method is common in the early design stage as it is both fast and known to give accurate results (ITTC 2011). Higher fidelity approaches for response calculations exist, for instance 3D potential theory methods (Söding and Bertram 2009) and computational fluid dynamics (CFD) (Kim 2011), where fourier transform of the response time series can be used to estimate vessel RAOs. In practice, these methods require extensive computational effort and skill to be performed successfully.…”

Section: Response Characteristicsmentioning

confidence: 99%

A simulation-based ship design methodology for evaluating susceptibility to weather-induced delays during marine operations

Sandvik

Gutsch

Asbjørnslett

2018

Ship Technology Research

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In this paper, we present and test a discrete-event simulation approach for evaluating the inherent susceptibility to weather-induced delays during marine operations as a consequence of limitations in vessel response characteristics. The simulation routine replicates the execution of operations in a long-term perspective by applying weather data time series and vessel response-based operational criteria. Weather windows are taken as the basis for the operation start-up criterion. A case study is presented where we examine the capabilities of the simulation methodology towards reflecting the inherent weather challenges in operational scenarios and the ability to distinguish between alternative design concepts. Comparison is performed towards the percentage operability method and integrated operability factor to uncover advantages of the presented approach. Application of the simulation methodology is found to yield further knowledge of the inherent operational persistence and weather delay susceptibility of proposed vessel designs in the early phases of ship design.

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A 3-d Rankine Source Seakeeping Method

Cited by 17 publications

References 1 publication

Rankine Source Method for Ship–Ship Interaction Problems

Rankine Source Method for Ship–Ship Interaction Problems

Linear and Nonlinear Sectional Loads With Potential and Field Methods

A simulation-based ship design methodology for evaluating susceptibility to weather-induced delays during marine operations

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