Predicted wave field in a laboratory wave basin

1990 ◽  
Vol 17 (6) ◽  
pp. 1005-1014 ◽  
Author(s):  
Michael Isaacson ◽  
Shiqin Qu
Keyword(s):  
Wave Field ◽  
Wave Diffraction ◽  
Diffraction Theory ◽  
Ocean Engineering ◽  
Laboratory Facilities ◽  
Rectangular Basin ◽  
Diffraction Wave ◽  
Wave Basin ◽  
Wave Generator ◽  
Reflection Boundary

The present paper describes a numerical method for predicting the wave field produced by a segmented wave generator undergoing specified motions in a wave basin which may contain partially reflecting sides. The approach used is based on linear diffraction theory and utilizes a point source representation of the generator segments and any reflecting walls that are present. The method involves the application of a partial reflection boundary condition, which is discussed. Numerical results are presented for the propagating wave field due to specified wave generator motions in a rectangular basin. Cases that are considered include both perfectly absorbing and partially reflecting beaches along the basin sides, as well as the presence of perfectly reflecting short sidewalls near the generator. The method appears able to account adequately for the effects of wave diffraction and partial reflections, and to predict the generated wave field realistically. Key words: coastal engineering, hydrodynamics, laboratory facilities, ocean engineering, wave diffraction, wave generation, wave reflection.

Reflection effects on wave field within a harbour

1993 ◽  
Vol 20 (3) ◽  
pp. 386-397 ◽  
Author(s):  
Michael Isaacson ◽  
Enda O'Sullivan ◽  
John Baldwin
Keyword(s):  
Numerical Model ◽  
Wave Field ◽  
Wave Reflection ◽  
Diffraction Theory ◽  
Specific Reference ◽  
Wave Source ◽  
Numerical Predictions ◽  
Diffraction Wave ◽  
Reflecting Boundaries ◽  
Reflection Boundary

The present paper outlines a numerical model for predicting the wave field in a harbour with partially reflecting boundaries, and describes laboratory tests undertaken to assess the model. The numerical model is based on linear diffraction theory and involves the application of a partial reflection boundary condition. By utilizing a wave doublet representation of the fluid boundaries instead of the usual wave source representation, the extension is made to general harbour configurations that include breakwaters. Numerical results are compared with known solutions for specific reference configurations. Laboratory measurements have been made of the wave field within a particular harbour model having portions of the boundary corresponding to different degrees of wave reflection. A comparison with the numerical predictions is summarized and highlights the importance of adequately modelling the partial reflections within the harbour. Key words: breakwaters, coastal engineering, harbours, waves, wave diffraction, wave reflection.

Wave-Vessel Interactions in Beam Seas

2009 ◽  
Author(s):  
Eirini Spentza ◽  
Chris Swan
Keyword(s):  
Wave Field ◽  
Incident Wave ◽  
Laboratory Data ◽  
Wave Structure ◽  
Wave Pattern ◽  
Scaled Model ◽  
Beam Seas ◽  
Wave Basin ◽  
Wave Slamming ◽  
Speed Of Propagation

This paper concerns the nonlinear interaction of waves with a floating vessel. A detailed experimental study has been undertaken in a 3-D wave basin, using a scaled model tanker subject to a variety of incident wave conditions. The vessel, which is free to move in heave, pitch and roll, has a draft of 14m (at full-scale) and is subject to a range of incident wave periods propagating at right angles to the side shell of the vessel. Measurements undertaken with and without the vessel in place allow the diffracted-radiated wave field to be identified. The laboratory data indicate that the diffracted-radiated wave pattern varies significantly with the incident wave period. Detailed analysis of the experimental results has identified a hitherto unexpected second-order freely propagating wave harmonic generated due to the presence of the vessel. Given its frequency content and its relatively slow speed of propagation, this harmonic leads to a significant steepening of the wave field around the vessel and therefore has an important role to play in terms of the occurrence of wave slamming. Physical insights are provided concerning the latter and the practical implications of the overall wave-structure interactions are considered.

Optical theorem for multipole sources in wave diffraction theory

2016 ◽  
Vol 62 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Yu. A. Eremin ◽  
A. G. Sveshnikov
Keyword(s):  
Wave Diffraction ◽  
Diffraction Theory ◽  
Optical Theorem ◽  
Multipole Sources

Generation of a spatially periodic directional wave field in a rectangular wave basin based on higher-order spectral simulation

2018 ◽  
Vol 169 ◽  
pp. 428-441 ◽  
Author(s):  
Hidetaka Houtani ◽  
Takuji Waseda ◽  
Wataru Fujimoto ◽  
Keiji Kiyomatsu ◽  
Katsuji Tanizawa
Keyword(s):  
Wave Field ◽  
Higher Order ◽  
Spectral Simulation ◽  
Rectangular Wave ◽  
Wave Basin ◽  
Spatially Periodic ◽  
Directional Wave

scholarly journals Wave field reconstruction and phase imaging by electron diffractive imaging

Microscopy ◽  
2020 ◽  
Author(s):  
Jun Yamasaki
Keyword(s):  
Wave Field ◽  
Real Space ◽  
Phase Image ◽  
Phase Imaging ◽  
Diffractive Imaging ◽  
Diffraction Wave ◽  
Phase Images ◽  
Applicable Range ◽  
The Fourier Transform

Abstract In electron diffractive imaging, the phase image of a sample is reconstructed from its diffraction intensity through iterative calculations. The principle of this method is based on the Fourier transform relation between the real-space wave field transmitted by the sample and its Fraunhofer diffraction wave field. Since Gerchberg’s experimental work in 1972, various advancements have been achieved, which have substantially improved the quality of the reconstructed phase images and extended the applicable range of the method. In this review article, the principle of diffractive imaging, various experimental processes using electron beams and application to specific samples are explained in detail.

The reduction of a pair of singular integral equations

1986 ◽  
Vol 100 (1) ◽  
pp. 175-182 ◽  
Author(s):  
D. Porter
Keyword(s):  
Integral Equations ◽  
Singular Integral ◽  
Wave Diffraction ◽  
Reduction Process ◽  
Singular Integral Equations ◽  
Diffraction Theory ◽  
Single Equation ◽  
Fredholm Equations ◽  
Type Reduction ◽  
Reduction Methods

AbstractA method is derived for converting a pair of coupled singular integral equations of a certain form into a single equation of the same (Cauchy-separable) type. Reduction methods for systems of singular integral equations are generally directed towards the construction of equivalent Fredholm equations. Preservation of the singular nature of the kernel in the reduction process permits the powerful techniques associated with Cauchy kernels to be used in seeking closed solutions of the original pair.The example given, derived previously from a problem in wave diffraction theory, illustrates many aspects of the method.

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