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Investigation of coupled sway, roll and yaw motions of a floating body: numerical modelling for non-linear restoring

journal contribution
posted on 2023-05-16, 22:31 authored by Das, SK, Das, SN, Sahoo, PK
The article deals with the numerical modelling of sway, roll and yaw motions of a floating body in time domain and investigates motion instability primarily due to non-linear roll restoring characteristics in the absence of auto piloting mechanism. To compute hydrodynamic forces, we consider non-linear roll restoring characteristics and speed dependent strip theory that are obtained from the Frank's close-fit method. The governing equations are solved numerically by using RungeKutta- Gill method with adaptive step size adjustment algorithm. In order to illustrate non-linear roll restoring effect in sway.troll and yaw, numerical experiments have been carried out for a Panamax container ship under the action of sinusoidal wave of periodicity 11.2 s with varying wave height and speed. To emulate the soft spring behaviour in roll, the expression for non-linear restoring moment is represented by an odd order polynomial of roll angle. Further, in the absence of zero restoring mechanism in sway and yaw, the effect of initial condition, wave height and ship's speed is examined in terms of ship's stability. This approach provides an important guideline to model non-linear roll restoring moment for a coupled system in three degrees of freedom.

History

Publication title

Ships and Offshore Structures

Pagination

49-56

ISSN

1744-5302

Department/School

Australian Maritime College

Publisher

Taylor & francis

Place of publication

UK

Rights statement

The definitive published version is available online at: http://www.tandf.co.uk/journals

Repository Status

  • Restricted

Socio-economic Objectives

International sea freight transport (excl. live animals, food products and liquefied gas)

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