dc.contributor |
Universitat Politècnica de Catalunya. Departament de Física |
dc.contributor |
Universitat Politècnica de Catalunya. DF - Dinàmica de Fluids: formació d'estructures i aplicacions geofísiques |
dc.contributor.author |
Falqués Serra, Albert |
dc.contributor.author |
Kakeh Burgada, Nabil |
dc.contributor.author |
Calvete Manrique, Daniel |
dc.date |
2018-06-27 |
dc.identifier.citation |
Falques, A., Kakeh, N., Calvete, D. A new instability mechanism related to high-angle waves. "Ocean dynamics", 27 Juny 2018, p. 1-11. |
dc.identifier.citation |
1616-7341 |
dc.identifier.citation |
10.1007/s10236-018-1186-0 |
dc.identifier.uri |
http://hdl.handle.net/2117/120458 |
dc.language.iso |
eng |
dc.relation |
https://link.springer.com/article/10.1007%2Fs10236-018-1186-0 |
dc.rights |
Attribution-NonCommercial-NoDerivs 3.0 Spain |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.rights |
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
dc.subject |
Àrees temàtiques de la UPC::Física |
dc.subject |
Waves |
dc.subject |
Coastal geomorphology |
dc.subject |
Self-organized patterns |
dc.subject |
High-angle waves |
dc.subject |
Shore-oblique sand bars |
dc.subject |
Ones |
dc.title |
A new instability mechanism related to high-angle waves |
dc.type |
info:eu-repo/semantics/submittedVersion |
dc.type |
info:eu-repo/semantics/article |
dc.description.abstract |
Waves with a large incidence angle in deep water can drive a morphodynamic instability on a sandy coast whereby shoreline sand waves, cuspate forelands, and spits can emerge. This instability is related to bathymetric perturbations extending offshore in the shoaling zone. Here, we explore a different mechanism where the large incidence angle is supposed to occur at breaking and the bathymetric perturbations occur only in the surf zone. For wave incidence angles at breaking above ˜¿45°, the one-line approximation of coastal dynamics predicts an unstable shoreline. This instability (EHAWI) is scale-free and the growth rate increases without bound for decreasing wavelength. Here we use a 2DH morphodynamic model resolving surf zone instabilities to investigate whether EHAWI could approximate a real instability in nature with a characteristic length scale. Assuming very idealized conditions on the bathymetric profile and sediment transport, we find a 2DH instability mode consisting of shore-oblique up-current bars coupled to a meandering of the longshore current. This mode grows for high-angle waves, above about 30° (offshore) and the maximum growth rate occurs for the angle maximizing the angle at breaking, about 70° (offshore). The dominant wavelength is of the order of the surf zone width. Interestingly, for long sand waves, the growth rate never becomes negative and it matches very well the anti-diffusive behavior of EHAWI. This distinguishes the present instability mode from other modes found in previous studies for other bathymetric and sediment transport conditions. Thus, we conclude that EHAWI approximates a real morphodynamic instability only for quite particular conditions. In such case, a characteristic length scale of the instability emerges thanks to surf zone processes that damp short wavelengths. |