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Generation and nonlinear evolution of shore-oblique/transverse sand bars

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dc.contributor Universitat de Vic. Escola Politècnica Superior
dc.contributor Universitat de Vic. Grup de Recerca de Medi Ambient
dc.contributor.author Garnier, R.
dc.contributor.author Calvete, D.
dc.contributor.author Falqués, Albert
dc.contributor.author Caballeria, Miquel
dc.date.accessioned 2012-10-08T10:20:28Z
dc.date.available 2012-10-08T10:20:28Z
dc.date.created 2006
dc.date.issued 2006
dc.identifier.citation GARNIER, R. i altres . "Generation and nonlinear evolution of shore-oblique/transverse sand bars". A: Journal of Fluid Mechanics, 2006, vol. 567, pàg. 327-360. DOI: 10.1017/S0022112006002126, ca_ES
dc.identifier.issn 0022-1120
dc.identifier.uri http://hdl.handle.net/10854/1892
dc.description.abstract The coupling between topography, waves and currents in the surf zone may selforganize to produce the formation of shore-transverse or shore-oblique sand bars on an otherwise alongshore uniform beach. In the absence of shore-parallel bars, this has been shown by previous studies of linear stability analysis, but is now extended to the finite-amplitude regime. To this end, a nonlinear model coupling wave transformation and breaking, a shallow-water equations solver, sediment transport and bed updating is developed. The sediment flux consists of a stirring factor multiplied by the depthaveraged current plus a downslope correction. It is found that the cross-shore profile of the ratio of stirring factor to water depth together with the wave incidence angle primarily determine the shape and the type of bars, either transverse or oblique to the shore. In the latter case, they can open an acute angle against the current (upcurrent oriented) or with the current (down-current oriented). At the initial stages of development, both the intensity of the instability which is responsible for the formation of the bars and the damping due to downslope transport grow at a similar rate with bar amplitude, the former being somewhat stronger. As bars keep on growing, their finite-amplitude shape either enhances downslope transport or weakens the instability mechanism so that an equilibrium between both opposing tendencies occurs, leading to a final saturated amplitude. The overall shape of the saturated bars in plan view is similar to that of the small-amplitude ones. However, the final spacings may be up to a factor of 2 larger and final celerities can also be about a factor of 2 smaller or larger. In the case of alongshore migrating bars, the asymmetry of the longshore sections, the lee being steeper than the stoss, is well reproduced. Complex dynamics with merging and splitting of individual bars sometimes occur. Finally, in the case of shore-normal incidence the rip currents in the troughs between the bars are jet-like while the onshore return flow is wider and weaker as is observed in nature. ca_ES
dc.format application/pdf
dc.format.extent 35 p. ca_ES
dc.language.iso eng ca_ES
dc.publisher Cambridge University Press ca_ES
dc.rights (c) Cambridge University Press. The published version of the article:GARNIER, R. i altres . "Generation and nonlinear evolution of shore-oblique/transverse sand bars". A: Journal of Fluid Mechanics, 2006, vol. 567, pàg. 327-360. DOI: 10.1017/S0022112006002126 , is available at http://journals.cambridge.org
dc.subject.other Hidràulica ca_ES
dc.subject.other Mecànica de fluïds ca_ES
dc.title Generation and nonlinear evolution of shore-oblique/transverse sand bars ca_ES
dc.type info:eu-repo/semantics/article ca_ES
dc.identifier.doi https://doi.org/10.1017/S0022112006002126
dc.relation.publisherversion http://journals.cambridge.org/action/displayJournal?jid=FLM
dc.rights.accesRights info:eu-repo/semantics/openAccess
dc.type.version info:eu-repo/semantics/publishedVersion
dc.indexacio Indexat a SCOPUS
dc.indexacio Indexat a WOS/JCR ca_ES

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