Dispersive Wave Focusing on a Shear Current: Part 1—Linear Approximations - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Water Waves Année : 2024

Dispersive Wave Focusing on a Shear Current: Part 1—Linear Approximations

Résumé

We consider the evolution and kinematics during dispersive focussing, for a group of waves propagating atop currents varying with depth. Our analysis assumes long-crested linear waves propagating at arbitrary angles relative to the current. Although low steepness is assumed, the linear model is often a reasonable approximation for understanding rogue waves. A number of analytical approximate relations are derived assuming different sub-surface current profiles, including linearly varying current, exponentially varying current, and currents of arbitrary depth profile which are weakly sheared following the approximation of Stewart and Joy (Deep Sea Res. Abs. 21 , 1974). The orbital velocities are likewise studied. While shear currents have modest influence on the motion of the envelope of the wave group, they significantly change wave kinematics. Horizontal orbital velocities are either amplified or suppressed depending on whether the shear is opposing or following, respectively. To illustrate these phenomena we consider a real-world example using velocity profiles and wave spectra measured in the Columbia River estuary. Near the surface at the point where focusing occurs, horizontal orbital velocities are, respectively, increased and decreased by factors of 1.4 and 0.7 for focusing groups propagating on following and opposing shear (respectively, upstream and downstream in the earth-fixed reference system). The implications for the forces a focusing wave group can exert on vessels and installations are profound, emphasising the importance of considering current profiles in maritime operations.
Fichier principal
Vignette du fichier
Dispersive_focussing__Pt1___linear_theory.pdf (3.18 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-04535288 , version 1 (06-04-2024)

Identifiants

Citer

Simen Å. Ellingsen, Zibo Zheng, Malek Abid, Christian Kharif, Yan Li. Dispersive Wave Focusing on a Shear Current: Part 1—Linear Approximations. Water Waves, inPress, ⟨10.1007/s42286-024-00085-3⟩. ⟨hal-04535288⟩
2 Consultations
4 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More