eprintid: 10124192 rev_number: 20 eprint_status: archive userid: 608 dir: disk0/10/12/41/92 datestamp: 2021-03-18 14:46:35 lastmod: 2021-10-29 06:10:21 status_changed: 2021-03-18 14:46:35 type: article metadata_visibility: show creators_name: Johnson, E creators_name: Crowe, M title: The decay of a dipolar vortex in a weakly dispersive environment ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F59 note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: A simple model is presented for the evolution of a dipolar vortex propagating horizontally in a vertical-slice model of a weakly stratified inviscid atmosphere, following the model of Flierl & Haines (Phys. Fluids, vol. 6, 1994, pp. 3487–3497) for a modon on the beta-plane. The dipole is assumed to evolve to remain within the family of Lamb–Chaplygin dipoles but with varying radius and speed. The dipole loses energy and impulse through internal wave radiation. It is argued, and verified against numerical solutions of the full equations, that an appropriately defined centre vorticity for the dipole is closely conserved throughout the flow evolution. Combining conservation of centre vorticity with the requirement that the dipole energy loss balances the work done on the fluid by internal wave radiation gives a model that captures much of the observed dipole decay. Similar results are noted for a cylindrical dipole propagating along the axis of a rotating fluid when the dipole axis is perpendicular to the axis of rotation and for a spherical vortex propagating horizontally in a weakly stratified fluid. The model extends to fluids of small viscosity and so provides an estimate for the relative importance of wave drag and dissipation in dipole decay. date: 2021-06-25 date_type: published publisher: Cambridge University Press official_url: https://doi.org/10.1017/jfm.2021.298 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1853931 doi: 10.1017/jfm.2021.298 lyricists_name: Crowe, Matthew lyricists_name: Johnson, Edward lyricists_id: MNCRO25 lyricists_id: ERJOH80 actors_name: Johnson, Edward actors_id: ERJOH80 actors_role: owner full_text_status: public publication: Journal of Fluid Mechanics volume: 917 article_number: A35 citation: Johnson, E; Crowe, M; (2021) The decay of a dipolar vortex in a weakly dispersive environment. Journal of Fluid Mechanics , 917 , Article A35. 10.1017/jfm.2021.298 <https://doi.org/10.1017/jfm.2021.298>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10124192/1/StratifiedBeta%20.pdf