Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models

Morten Christensen

Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models

Morten Christensen

Publikation: Ph.d.-afhandling

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Abstract

Metoder til mekanisk generering af 2-dimensionale (2-D) og 3-dimensionale (3-D) lineære bølger i fysiske modeller præsenteres. Resultaterne af en række laboratorie 3-D bølgegenereringsforsøg præsenteres og diskuteres. Forsøgene omfatter reproduktion af bølgefelter karakteriseret ved forskellige retningsspektre. De anvendte bølgegeneratorflytningssignaler genereres vha. liniær digital filtrering af Gaussisk hvid støj i tidsdomænet. En absorberende bølgegenerator til 2-D laboratoriefaciliteter (bølgekanaler) udvikles. Den absorberende bølgegenerator er baseret på et nyt princip for aktiv absorption af reflekterende bølger: Bølgegeneratorflytningskorrektionssignalet svarende til absorption af det reflekterede bølgetog fastlægges vha. liniær filtrering og efterfølgende superposition af overfladeelevationssignaler målt i to positioner i bølgekanalen foran bølgegeneratoren. Resultaterne af laboratorieforsøg udført med en absorberende bølgegenerator baseret på dette princip viser at problemer med rerefleksion reduceres væsentligt når artiv absorption foretages.
Endvidere udvikles en absorberende 3-D bølgegenerator baseret på et ligende princip. En konventionel 3-D bølgegenerator laves om til en absorberende bølgegenerator baseret på dette princip, og en række laboratorieforsøg udføres med denne bølgegenerator. Forsøgsresultaterne viser, at den absorberende 3-D bølgegenerator er i sand til at reducere problemerne med rerefleksion i retningsspredte, uregelmæssige bølgefelter væsentlig.

Originalsprog	Engelsk
Udgivelsessted	Aalborg
Udgiver	Hydraulics & Coastal Engineering Laboratory, Department of Civil Engineering, Aalborg University
Status	Udgivet - 1995

Bibliografisk note

PDF for print: 128 pp.

Emneord

Waves
Wave Absorption
2-D Wave Generation
3-D Wave Generation
2-D Wave Absorption
3-D Wave Absorption
Physical Model Tests

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Generation and Active Absorption of 2 and 3 Dimensional Linear Water Waves in Physical ModelsForlagets udgivne version, 16,7 MB

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title = "Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models",

abstract = "Methods for mechanical generation of 2-dimensional (2-D) and 3-dimensional (3-D) linear water waves in physical models are presented. The results of a series of laboratory 3-D wave generation tests are presented and discussed. The tests preformed involve reproduction of wave fields characterised by different directional wave spectra. The wave generator displacement signals applied in the tests are generated by means of linear digital filtering of Gaussian white noise in the time domain. An absorbing wave generator for 2-D wave facilities (wave channels) is developed. The absorbing wave generator is based on a new principle for active absorption of reflected waves: the wave generator displacement correction signal corresponding to absorption of the reflected wave train is determined by means of linear filtering and subsequent superposition of surface elevation signals measured in two positions in the wave channel in front of the wave generator. The results of physical model tests performed with an absorbing wave maker based on this principle show that the problem of rereflection is reduced significantly when active absorption is performed. Finally, an absorbing directional wave generator for 3-D wave facilities (wave basins) based on a similar principle is developed. A conventional directional wave generator is converted into an absorbing directional wave generator based on this principle and applied to a series of physical model tests. The test results show that the absorbing directional wave generator is capable of of reducing the problem of rereflection in multidirectional, irregular wave fields significantly. ",

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N2 - Methods for mechanical generation of 2-dimensional (2-D) and 3-dimensional (3-D) linear water waves in physical models are presented. The results of a series of laboratory 3-D wave generation tests are presented and discussed. The tests preformed involve reproduction of wave fields characterised by different directional wave spectra. The wave generator displacement signals applied in the tests are generated by means of linear digital filtering of Gaussian white noise in the time domain. An absorbing wave generator for 2-D wave facilities (wave channels) is developed. The absorbing wave generator is based on a new principle for active absorption of reflected waves: the wave generator displacement correction signal corresponding to absorption of the reflected wave train is determined by means of linear filtering and subsequent superposition of surface elevation signals measured in two positions in the wave channel in front of the wave generator. The results of physical model tests performed with an absorbing wave maker based on this principle show that the problem of rereflection is reduced significantly when active absorption is performed. Finally, an absorbing directional wave generator for 3-D wave facilities (wave basins) based on a similar principle is developed. A conventional directional wave generator is converted into an absorbing directional wave generator based on this principle and applied to a series of physical model tests. The test results show that the absorbing directional wave generator is capable of of reducing the problem of rereflection in multidirectional, irregular wave fields significantly.

AB - Methods for mechanical generation of 2-dimensional (2-D) and 3-dimensional (3-D) linear water waves in physical models are presented. The results of a series of laboratory 3-D wave generation tests are presented and discussed. The tests preformed involve reproduction of wave fields characterised by different directional wave spectra. The wave generator displacement signals applied in the tests are generated by means of linear digital filtering of Gaussian white noise in the time domain. An absorbing wave generator for 2-D wave facilities (wave channels) is developed. The absorbing wave generator is based on a new principle for active absorption of reflected waves: the wave generator displacement correction signal corresponding to absorption of the reflected wave train is determined by means of linear filtering and subsequent superposition of surface elevation signals measured in two positions in the wave channel in front of the wave generator. The results of physical model tests performed with an absorbing wave maker based on this principle show that the problem of rereflection is reduced significantly when active absorption is performed. Finally, an absorbing directional wave generator for 3-D wave facilities (wave basins) based on a similar principle is developed. A conventional directional wave generator is converted into an absorbing directional wave generator based on this principle and applied to a series of physical model tests. The test results show that the absorbing directional wave generator is capable of of reducing the problem of rereflection in multidirectional, irregular wave fields significantly.

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KW - 3-D Wave Generation

KW - 2-D Wave Absorption

KW - 3-D Wave Absorption

KW - Physical Model Tests

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KW - Wave Absorption

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KW - 3-D Wave Generation

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KW - 3-D Wave Absorption

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M3 - PhD thesis

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ER -

Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models

Abstract

Bibliografisk note

Emneord

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