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A time-varying parameter model of a body oscillating in pitch.

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A time-varying parameter model of a body oscillating in pitch. / McCabe, A. P.; Aggidis, George A.; Stallard, T. J.

In: Applied Ocean Research, Vol. 28, No. 6, 12.2006, p. 359-370.

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McCabe, A. P. ; Aggidis, George A. ; Stallard, T. J. / A time-varying parameter model of a body oscillating in pitch. In: Applied Ocean Research. 2006 ; Vol. 28, No. 6. pp. 359-370.

Bibtex

@article{7250768b861948c4ad6f659b2b61af86,
title = "A time-varying parameter model of a body oscillating in pitch.",
abstract = "Among the assumptions upon which linear time-invariant models of floating bodies are based is that the body motions are so small that any change in the body{\textquoteright}s angular position can be disregarded. However, it is often a major design requirement of a wave energy conversion device that the response amplitude is large, thereby invalidating one of the assumptions of the linear model. In particular, the immersed geometry of a body undergoes considerable variation when it is moved in pitch. With regard to this we investigate the difference in performance between a quasi-linear model in which the change of immersed surface is modelled by time-varying parameters and a basic linear model in which the immersed surface is time-invariant. The time-varying parameter model is realized by interpolation between the appropriate parameter values of a set of linear time-invariant (LTI) models derived for the different immersed surfaces that occur at discrete body displacements. It is shown that the responses predicted using the time-varying parameter model are closer to those measured experimentally than those of a standard frequency-domain model. Particular improvement occurs when the responses are large, such as at or near the resonance frequency. A problem which may limit the general use of the model is also discussed.",
keywords = "Time-varying parameter model, Time-domain model, Potential-flow hydrodynamics",
author = "McCabe, {A. P.} and Aggidis, {George A.} and Stallard, {T. J.}",
year = "2006",
month = dec,
doi = "10.1016/j.apor.2007.05.001",
language = "English",
volume = "28",
pages = "359--370",
journal = "Applied Ocean Research",
issn = "0141-1187",
publisher = "Elsevier BV",
number = "6",

}

RIS

TY - JOUR

T1 - A time-varying parameter model of a body oscillating in pitch.

AU - McCabe, A. P.

AU - Aggidis, George A.

AU - Stallard, T. J.

PY - 2006/12

Y1 - 2006/12

N2 - Among the assumptions upon which linear time-invariant models of floating bodies are based is that the body motions are so small that any change in the body’s angular position can be disregarded. However, it is often a major design requirement of a wave energy conversion device that the response amplitude is large, thereby invalidating one of the assumptions of the linear model. In particular, the immersed geometry of a body undergoes considerable variation when it is moved in pitch. With regard to this we investigate the difference in performance between a quasi-linear model in which the change of immersed surface is modelled by time-varying parameters and a basic linear model in which the immersed surface is time-invariant. The time-varying parameter model is realized by interpolation between the appropriate parameter values of a set of linear time-invariant (LTI) models derived for the different immersed surfaces that occur at discrete body displacements. It is shown that the responses predicted using the time-varying parameter model are closer to those measured experimentally than those of a standard frequency-domain model. Particular improvement occurs when the responses are large, such as at or near the resonance frequency. A problem which may limit the general use of the model is also discussed.

AB - Among the assumptions upon which linear time-invariant models of floating bodies are based is that the body motions are so small that any change in the body’s angular position can be disregarded. However, it is often a major design requirement of a wave energy conversion device that the response amplitude is large, thereby invalidating one of the assumptions of the linear model. In particular, the immersed geometry of a body undergoes considerable variation when it is moved in pitch. With regard to this we investigate the difference in performance between a quasi-linear model in which the change of immersed surface is modelled by time-varying parameters and a basic linear model in which the immersed surface is time-invariant. The time-varying parameter model is realized by interpolation between the appropriate parameter values of a set of linear time-invariant (LTI) models derived for the different immersed surfaces that occur at discrete body displacements. It is shown that the responses predicted using the time-varying parameter model are closer to those measured experimentally than those of a standard frequency-domain model. Particular improvement occurs when the responses are large, such as at or near the resonance frequency. A problem which may limit the general use of the model is also discussed.

KW - Time-varying parameter model

KW - Time-domain model

KW - Potential-flow hydrodynamics

U2 - 10.1016/j.apor.2007.05.001

DO - 10.1016/j.apor.2007.05.001

M3 - Journal article

VL - 28

SP - 359

EP - 370

JO - Applied Ocean Research

JF - Applied Ocean Research

SN - 0141-1187

IS - 6

ER -