Higher Harmonics Induced by Waves Propagating over A Submerged Obstacle in the Presence of Uniform Current

To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume(NWF) is developed by use of a time-domain higher-order boundary element method(HOBEM) based on potential flow theory. A four-point method is developed to deco...

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Published inChina ocean engineering Vol. 28; no. 6; pp. 725 - 738
Main Author 宁德志 林红星 滕斌 邹青萍
Format Journal Article
LanguageEnglish
Published Heidelberg Chinese Ocean Engineering Society 01.12.2014
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ISSN0890-5487
2191-8945
DOI10.1007/s13344-014-0057-9

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Summary:To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume(NWF) is developed by use of a time-domain higher-order boundary element method(HOBEM) based on potential flow theory. A four-point method is developed to decompose higher bound and free harmonic waves propagating upstream and downstream around the obstacle. The model predictions are in good agreement with the experimental data for free harmonics induced by a submerged horizontal cylinder in the absence of currents. This serves as a benchmark to reveal the current effects on higher harmonic waves. The peak value of non-dimensional second free harmonic amplitude is shifted upstream for the opposing current relative to that for zero current with the variation of current-free incident wave amplitude, and it is vice versa for the following current. The second-order analysis shows a resonant behavior which is related to the ratio of the cylinder diameter to the second bound mode wavelength over the cylinder. The second-order resonant position slightly downshifted for the opposing current and upshifted for the following current.
Bibliography:higher harmonics wave-current interaction HOBEM free mode
32-1441/P
NING De-zhi, LIN Hong-xing , TENG Bin , ZOU Qing-ping ( a State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China b Department of Clvtl and Envwonmenta/ Engineering, University of Maine, Orono, ME 04469, USA)
To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume(NWF) is developed by use of a time-domain higher-order boundary element method(HOBEM) based on potential flow theory. A four-point method is developed to decompose higher bound and free harmonic waves propagating upstream and downstream around the obstacle. The model predictions are in good agreement with the experimental data for free harmonics induced by a submerged horizontal cylinder in the absence of currents. This serves as a benchmark to reveal the current effects on higher harmonic waves. The peak value of non-dimensional second free harmonic amplitude is shifted upstream for the opposing current relative to that for zero current with the variation of current-free incident wave amplitude, and it is vice versa for the following current. The second-order analysis shows a resonant behavior which is related to the ratio of the cylinder diameter to the second bound mode wavelength over the cylinder. The second-order resonant position slightly downshifted for the opposing current and upshifted for the following current.
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ISSN:0890-5487
2191-8945
DOI:10.1007/s13344-014-0057-9