Long wave generation by the shoaling and breaking of transient wave groups on a beach

Baldock, T. E. (2006) Long wave generation by the shoaling and breaking of transient wave groups on a beach. Proceedings of The Royal Society A: Mathematical Physical And Engineering Sciences, 462 2070: 1853-1876. doi:10.1098/rspa.2005.1642


Author Baldock, T. E.
Title Long wave generation by the shoaling and breaking of transient wave groups on a beach
Journal name Proceedings of The Royal Society A: Mathematical Physical And Engineering Sciences   Check publisher's open access policy
ISSN 1364-5021
Publication date 2006-06-01
Sub-type Article (original research)
DOI 10.1098/rspa.2005.1642
Volume 462
Issue 2070
Start page 1853
End page 1876
Total pages 24
Place of publication London, U.K.
Publisher Royal Society
Collection year 2006
Language eng
Subject C1
290899 Civil Engineering not elsewhere classified
770400 Coastal and Estuarine Environment
Abstract This paper presents new laboratory data on the generation of long waves by the shoaling and breaking of transient-focused short-wave groups. Direct offshore radiation of long waves from the breakpoint is shown experimentally for the first time. High spatial resolution enables identification of the relationship between the spatial gradients of the short-wave envelope and the long-wave surface. This relationship is consistent with radiation stress theory even well inside the surf zone and appears as a result of the strong nonlinear forcing associated with the transient group. In shallow water, the change in depth across the group leads to asymmetry in the forcing which generates significant dynamic setup in front of the group during shoaling. Strong amplification of the incident dynamic setup occurs after short-wave breaking. The data show the radiation of a transient long wave dominated by a pulse of positive elevation, preceded and followed by weaker trailing waves with negative elevation. The instantaneous cross-shore structure of the long wave shows the mechanics of the reflection process and the formation of a transient node in the inner surf zone. The wave run-up and relative amplitude of the radiated and incident long waves suggests significant modification of the incident bound wave in the inner surf zone and, the dominance of long waves generated by the breaking process. It is proposed that these conditions occur when the primary short waves and bound wave are not shallow water waves at the breakpoint. A simple criterion is given to determine these conditions, which generally occur for the important case of storm waves.
Keyword Multidisciplinary Sciences
Transient Wave Groups
Long Waves
Surf Beat
Infragravity Waves
Swash
Rogue Waves
Surface Gravity-waves
Zone Dynamics
Water Waves
Run-up
Bars
Breakpoint
Bottom
Models
Shelf
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 18:54:15 EST