Mechanisms controlling crescentic bar amplitude

The formation of crescentic bars from self-organization of an initially straight shore-parallel bar for shore-normal incident waves is simulated with a two-dimensional horizontal morphodynamical model. The aim is to investigate the mechanisms behind the saturation process defined as the transition b...

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Detalles Bibliográficos
Autores: Garnier, Roland, Dodd, Nicholas, Falqués Serra, Albert|||0000-0002-3945-1509, Calvete Manrique, Daniel|||0000-0002-5402-5137
Tipo de recurso: artículo
Fecha de publicación:2010
País:España
Institución:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/8285
Acceso en línea:https://hdl.handle.net/2117/8285
https://dx.doi.org/10.1029/2009JF001407
Access Level:acceso abierto
Palabra clave:Bars (Geomorphology)
Sand bars
Platges
Àrees temàtiques de la UPC::Física
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spelling Mechanisms controlling crescentic bar amplitudeGarnier, RolandDodd, NicholasFalqués Serra, Albert|||0000-0002-3945-1509Calvete Manrique, Daniel|||0000-0002-5402-5137Bars (Geomorphology)Sand barsPlatgesÀrees temàtiques de la UPC::FísicaThe formation of crescentic bars from self-organization of an initially straight shore-parallel bar for shore-normal incident waves is simulated with a two-dimensional horizontal morphodynamical model. The aim is to investigate the mechanisms behind the saturation process defined as the transition between the linear regime (maximum and constant growth of the crescentic pattern) and the saturated state (negligible growth). The global properties of the morphodynamical patterns over the whole computational domain are studied (“global analysis”). In particular, consideration of the balance of the potential energy of the emerging bar gives its growth rate from the difference between a production term (related to the positive feedback leading to the instability) and a damping term (from the gravity-driven downslope transport). The production is approximately proportional to the average over the domain of the cross-shore flow velocity times the bed level perturbation. The damping is essential for the onset of the saturation, but it remains constant while the production decreases. Thus, it is notable that the saturation occurs because of a weakening of the instability mechanism rather than an increase of the damping. A reason for the saturation of the crescentic bar growth is the change in bar shape from its initial stage rather than the growth in amplitude itself. This change is mainly characterized by the narrowing of the rip channels, the onshore migration of the crests, and the change in the mean beach profile due to alongshore variability. These properties agree with observations of mature rip channel systems in nature.20102010-04-1520102010-07-20journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/2117/8285https://dx.doi.org/10.1029/2009JF001407reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Attribution-NonCommercial-NoDerivs 3.0 Spainhttp://creativecommons.org/licenses/by-nc-nd/3.0/es/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/82852026-05-27T15:37:01Z
dc.title.none.fl_str_mv Mechanisms controlling crescentic bar amplitude
title Mechanisms controlling crescentic bar amplitude
spellingShingle Mechanisms controlling crescentic bar amplitude
Garnier, Roland
Bars (Geomorphology)
Sand bars
Platges
Àrees temàtiques de la UPC::Física
title_short Mechanisms controlling crescentic bar amplitude
title_full Mechanisms controlling crescentic bar amplitude
title_fullStr Mechanisms controlling crescentic bar amplitude
title_full_unstemmed Mechanisms controlling crescentic bar amplitude
title_sort Mechanisms controlling crescentic bar amplitude
dc.creator.none.fl_str_mv Garnier, Roland
Dodd, Nicholas
Falqués Serra, Albert|||0000-0002-3945-1509
Calvete Manrique, Daniel|||0000-0002-5402-5137
author Garnier, Roland
author_facet Garnier, Roland
Dodd, Nicholas
Falqués Serra, Albert|||0000-0002-3945-1509
Calvete Manrique, Daniel|||0000-0002-5402-5137
author_role author
author2 Dodd, Nicholas
Falqués Serra, Albert|||0000-0002-3945-1509
Calvete Manrique, Daniel|||0000-0002-5402-5137
author2_role author
author
author
dc.subject.none.fl_str_mv Bars (Geomorphology)
Sand bars
Platges
Àrees temàtiques de la UPC::Física
topic Bars (Geomorphology)
Sand bars
Platges
Àrees temàtiques de la UPC::Física
description The formation of crescentic bars from self-organization of an initially straight shore-parallel bar for shore-normal incident waves is simulated with a two-dimensional horizontal morphodynamical model. The aim is to investigate the mechanisms behind the saturation process defined as the transition between the linear regime (maximum and constant growth of the crescentic pattern) and the saturated state (negligible growth). The global properties of the morphodynamical patterns over the whole computational domain are studied (“global analysis”). In particular, consideration of the balance of the potential energy of the emerging bar gives its growth rate from the difference between a production term (related to the positive feedback leading to the instability) and a damping term (from the gravity-driven downslope transport). The production is approximately proportional to the average over the domain of the cross-shore flow velocity times the bed level perturbation. The damping is essential for the onset of the saturation, but it remains constant while the production decreases. Thus, it is notable that the saturation occurs because of a weakening of the instability mechanism rather than an increase of the damping. A reason for the saturation of the crescentic bar growth is the change in bar shape from its initial stage rather than the growth in amplitude itself. This change is mainly characterized by the narrowing of the rip channels, the onshore migration of the crests, and the change in the mean beach profile due to alongshore variability. These properties agree with observations of mature rip channel systems in nature.
publishDate 2010
dc.date.none.fl_str_mv 2010
2010-04-15
2010
2010-07-20
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/8285
https://dx.doi.org/10.1029/2009JF001407
url https://hdl.handle.net/2117/8285
https://dx.doi.org/10.1029/2009JF001407
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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