A validation study on mathematical models of speed and frequency dependence in seakeeping of high speed craft
A validation study on mathematical models of speed and frequency dependence in seakeeping of high speed craft
An extensive validation exercise is presented into the speed and frequency dependent solutions associated with surface piercing vessels travelling in waves. The basis of the study lies in the formulations of the Green's function associated with a translating pulsating source. This method is applicable to vessels of arbitrary geometry and travelling with any forward speed; however the current validation exercise is focused on its application to high speed craft.
Two widely different mathematical formulations, and hence numerical schemes, are used to calculate the Green's function of a travelling and oscillating point source. These same methods are applied to calculate the hydrodynamic coefficients and wave loads of a surface piercing ellipsoid, a Series 60 cargo ship, a high speed NPL mono-hull and a simple multi-hull form. For each of these vessel types a range of forward speeds and frequencies of oscillation are considered. In each case very close agreement is observed in the quantities predicted by the two methods.
The validation process is continued for a Series 60 cargo ship through an investigation into the effects of changing the numerical idealisation of the hull form. A comparison of predicted hydrodynamic coefficients, wave loads and responses to regular waves with experimental data, as well as with other contemporary analytical techniques, provides further confidence in the adopted numerical methods.
The mathematical model is applied to predict the responses of a high speed mono-hull and two catamaran configurations travelling with three forward speeds. Through comparison with experimental data and simpler numerical methods the suitability of a translating pulsating source method to describe the changing nature of the fluid interaction between the hulls of a catamaran as speed changes is demonstrated. A further comparison between predicted and measured data for the two catamaran configurations travelling in oblique waves at one forward speed shows the translating pulsating source method to predict correctly the trends in response as heading changes. The versatility of such a numerical method is emphasised through calculations for an alternative high speed catamaran form.
The shortcomings of the translating pulsating source methods are discussed with reference to the assumptions made in developing the mathematical model; specifically those of an inviscid fluid, linearity and the simplification of the steady state flow.
University of Southampton
1999
Hudson, Dominic A
(1999)
A validation study on mathematical models of speed and frequency dependence in seakeeping of high speed craft.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
An extensive validation exercise is presented into the speed and frequency dependent solutions associated with surface piercing vessels travelling in waves. The basis of the study lies in the formulations of the Green's function associated with a translating pulsating source. This method is applicable to vessels of arbitrary geometry and travelling with any forward speed; however the current validation exercise is focused on its application to high speed craft.
Two widely different mathematical formulations, and hence numerical schemes, are used to calculate the Green's function of a travelling and oscillating point source. These same methods are applied to calculate the hydrodynamic coefficients and wave loads of a surface piercing ellipsoid, a Series 60 cargo ship, a high speed NPL mono-hull and a simple multi-hull form. For each of these vessel types a range of forward speeds and frequencies of oscillation are considered. In each case very close agreement is observed in the quantities predicted by the two methods.
The validation process is continued for a Series 60 cargo ship through an investigation into the effects of changing the numerical idealisation of the hull form. A comparison of predicted hydrodynamic coefficients, wave loads and responses to regular waves with experimental data, as well as with other contemporary analytical techniques, provides further confidence in the adopted numerical methods.
The mathematical model is applied to predict the responses of a high speed mono-hull and two catamaran configurations travelling with three forward speeds. Through comparison with experimental data and simpler numerical methods the suitability of a translating pulsating source method to describe the changing nature of the fluid interaction between the hulls of a catamaran as speed changes is demonstrated. A further comparison between predicted and measured data for the two catamaran configurations travelling in oblique waves at one forward speed shows the translating pulsating source method to predict correctly the trends in response as heading changes. The versatility of such a numerical method is emphasised through calculations for an alternative high speed catamaran form.
The shortcomings of the translating pulsating source methods are discussed with reference to the assumptions made in developing the mathematical model; specifically those of an inviscid fluid, linearity and the simplification of the steady state flow.
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Published date: 1999
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Local EPrints ID: 463931
URI: http://eprints.soton.ac.uk/id/eprint/463931
PURE UUID: 6cd32981-0ecb-4dc0-ade7-61ce0c3969ff
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Date deposited: 04 Jul 2022 20:58
Last modified: 04 Jul 2022 20:58
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Author:
Dominic A Hudson
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