Thesis

Time domain mathematical model for six-degree-of-freedom motion in a wave

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Awarding institution
  • University of Strathclyde
Date of award
  • 2009
Thesis identifier
  • T12389
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Abstract
  • To assess the behaviour of a ship in a seaway, this thesis presents the development of an integrated mathematical model describing a six-degree-of-freedom motion of a ship in a wave. This integrated mathematical model is developed with its fundamental base on both traditional seakeeping and manoeuvring theories and thus obtaining of hydrodynamic data sets as well as formulation of force component are needed in a theoretical manner. To obtain the hydrodynamic data sets, theoretical formulations and numerical implementations are carried out for a ship travelling in a wave. The theoretical formulation of three-dimensional potential flow leads boundary integral equations over mean wetted body surface with three-dimensional translating pulsating Green function. For numerical implementation Constant Panel Method and Higher-Order Panel Method are introduced as distribution technique of source singularities over the idealised body surface and compared for the estimation of hydrodynamic data set of Wigley and Todd Series 60. Mean second-order wave forces are formulated based on the solution of first-order problem and obtained by direct pressure integration over mean wetted body surface. The effects of forward speed and wave heading on the drift force and added resistance are investigated and compare with experimental data. An integrated mathematical model for manoeuvring motion is further developed with functional form of memory effect represented by convolution integrals of impulse response function to describe arbitrary ship motion in a seaway. For validation of developed numerical tool, benchmark tests have been performed for the prediction of large amplitude ship motion in following seas. Standard manoeuvring tests, turning circle and zig-zag manoeuvres, are presented to demonstrate the wave effects on the manoeuvring performance. The capability of numerical tool has been extended to the prediction of highly non-linear behaviours of parametric rolling phenomenon in longitudinal wave with reasonable accuracy.
Resource Type
DOI
EThOS ID
  • uk.bl.ethos.510740
Date Created
  • 2009
Former identifier
  • 805061

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