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Resolving wave and laminar boundary layer scales for gap resonance problems

Published online by Cambridge University Press:  18 March 2019

H. Wang*
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
H. A. Wolgamot
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
S. Draper
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
W. Zhao
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
P. H. Taylor
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
L. Cheng
Affiliation:
Faculty of Engineering and Mathematical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
*
Email address for correspondence: hongchao.wang2013@gmail.com

Abstract

Free surface oscillations in a narrow gap between elongated parallel bodies are studied numerically. As this represents both a highly resonant system and an arrangement of relevance to offshore operations, the nature of the damping is of primary interest, and has a critical role in determining the response. Previous experimental work has suggested that the damping could be attributed to laminar boundary layers; here our numerical wave tank successfully resolves both wave and boundary layer scales to provide strong numerical evidence in support of this conclusion. The simulations follow the experiments in using wave groups so that the computation is tractable, and both linear and second harmonic excitation of the gap are demonstrated.

Type
JFM Papers
Copyright
© 2019 Cambridge University Press 

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Wang et al. supplementary movie

Movie 1 (for mesh A3) shows the numerically computed free surface elevation around the boxes during passage of the incident transient wave group for Case A (in the region 2.5 m < x < 8.5 m, -4.0 m < y < 0 m, which is not the full extent of the NWT). Note that the vertical axis is stretched, such that 1 unit in the vertical = 5 units in the horizontal, to more clearly show the free surface motions. To this end, the boxes are shown as transparent.

Download Wang et al. supplementary movie(Video)
Video 9.3 MB