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Generation of nonlinear internal waves by flow over topography: Rotational effects

Yuan, C; Grimshaw, R; Johnson, E; Whitfield, A; (2020) Generation of nonlinear internal waves by flow over topography: Rotational effects. Physical Review E , 101 (3) , Article 033104. 10.1103/PhysRevE.101.033104. Green open access

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Abstract

We use the forced Ostrovsky equation to investigate the generation of internal waves excited by a constant background current flowing over localized topography in the presence of background rotation. As is now well known in the absence of background rotation, the evolution scenarios fall into three cases, namely subcritical, transcritical, and supercritical. Here an analysis of the linearized response divides the waves into steady and unsteady waves. In all three cases, steady waves occur downstream but no steady waves can occur upstream, while unsteady waves can arise upstream only when there is a negative minimum of the group velocity. The regions occupied by the steady and unsteady waves are determined by their respective group velocities. When the background current is increased, the wave number of the steady waves decreases. In addition, the concavity (canyon or sill), the topographic width, and the relative strength of the rotation play an important role in the generation mechanism. Nonlinear effects modulate the wave amplitude and lead to the emergence of coherent wave packets. All these findings are confirmed by numerical simulations.

Type: Article
Title: Generation of nonlinear internal waves by flow over topography: Rotational effects
Open access status: An open access version is available from UCL Discovery
DOI: 10.1103/PhysRevE.101.033104
Publisher version: https://doi.org/10.1103/PhysRevE.101.033104
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Mathematics
URI: https://discovery.ucl.ac.uk/id/eprint/10092946
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