Hydrodynamic behaviour of very large floating structures in waves
Hydrodynamic behaviour of very large floating structures in waves
An investigation upon the hydrodynamic/hydroelastic behaviour of two types (pontoon and semi-submersible) of Very Large Floating Structures (VLFS), free-floating with zero forward speed in regular waves is presented. This is achieved by means of both two-dimensional strip theories and three-dimensional source distribution method.
The investigation is carried out via two stages, namely dry and wet analyses. The dry or "in vacuo" analysis is achieved with aid from finite element method or/and suitable theoretical approaches. This analysis provides modal characteristics of the structure such as natural frequencies, principal mode shapes, modal internal actions (bending moments, torsional moments, direct and shear stresses, etc.), generalised masses.
To obtain the generalised added mass, hydrodynamic damping and wave excitation, the mean wetted surface is idealised using sections (i.e. strips) along the hull, for the two-dimensional analysis and a suitable distribution of four-cornered panels for the three-dimensional analysis. Lewis or multi-parameter conformal transformation techniques can be adopted for the two-dimensional analysis, whilst a pulsating source distribution over the mean wetted surface is used for the three-dimensional analysis. The resultant linear equations of motion are expressed in terms of principal coordinates, which are subsequently used to obtain responses of the structure.
Results in terms of resonant frequency, hydrodynamic loads and structural responses are compared between the two methods, two- and three-dimensional; and also between the two types of VLFS. Results of vertical displacement are also compared with available experiments.
A concept of "near-field" hydroelasticity is also proposed, where influences of panels far away from each other are neglected.
University of Southampton
2004
Phan, Th_uy Sy
(2004)
Hydrodynamic behaviour of very large floating structures in waves.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
An investigation upon the hydrodynamic/hydroelastic behaviour of two types (pontoon and semi-submersible) of Very Large Floating Structures (VLFS), free-floating with zero forward speed in regular waves is presented. This is achieved by means of both two-dimensional strip theories and three-dimensional source distribution method.
The investigation is carried out via two stages, namely dry and wet analyses. The dry or "in vacuo" analysis is achieved with aid from finite element method or/and suitable theoretical approaches. This analysis provides modal characteristics of the structure such as natural frequencies, principal mode shapes, modal internal actions (bending moments, torsional moments, direct and shear stresses, etc.), generalised masses.
To obtain the generalised added mass, hydrodynamic damping and wave excitation, the mean wetted surface is idealised using sections (i.e. strips) along the hull, for the two-dimensional analysis and a suitable distribution of four-cornered panels for the three-dimensional analysis. Lewis or multi-parameter conformal transformation techniques can be adopted for the two-dimensional analysis, whilst a pulsating source distribution over the mean wetted surface is used for the three-dimensional analysis. The resultant linear equations of motion are expressed in terms of principal coordinates, which are subsequently used to obtain responses of the structure.
Results in terms of resonant frequency, hydrodynamic loads and structural responses are compared between the two methods, two- and three-dimensional; and also between the two types of VLFS. Results of vertical displacement are also compared with available experiments.
A concept of "near-field" hydroelasticity is also proposed, where influences of panels far away from each other are neglected.
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Published date: 2004
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Local EPrints ID: 465445
URI: http://eprints.soton.ac.uk/id/eprint/465445
PURE UUID: e0bb744f-0971-4039-bbe2-afab65e393f8
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Date deposited: 05 Jul 2022 01:04
Last modified: 05 Jul 2022 01:04
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Author:
Th_uy Sy Phan
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