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Grid-based calculation of the Lagrangian mean

Kafiabad, Hossein A.

Authors



Abstract

Lagrangian averaging has been shown to be more effective than the Eulerian mean in separating waves from slow dynamics in two time scale flows. It also appears in many reduced models that capture the wave feedback on the slow flow. Its calculation, however, requires tracking particles in time, which imposes several difficulties in grid-based numerical simulations or estimation from fixed-point measurements. To circumvent these difficulties, we propose a grid-based iterative method to calculate the Lagrangian mean without tracking particles in time, which also reduces computation, memory footprint and communication between processors in parallelised numerical models. To assess the accuracy of this method several examples are examined and discussed. We also explore an application of this method in the context of shallow-water equations by quantifying the validity of wave-averaged geostrophic balance - a modified form of geostrophic balance accounting for the effect of strong waves on slow dynamics.

Citation

Kafiabad, H. A. (2022). Grid-based calculation of the Lagrangian mean. Journal of Fluid Mechanics, 940, Article A21. https://doi.org/10.1017/jfm.2022.233

Journal Article Type Article
Acceptance Date Mar 8, 2022
Online Publication Date Apr 8, 2022
Publication Date Jun 10, 2022
Deposit Date Apr 30, 2025
Journal Journal of Fluid Mechanics
Print ISSN 0022-1120
Electronic ISSN 1469-7645
Publisher Cambridge University Press
Peer Reviewed Peer Reviewed
Volume 940
Article Number A21
DOI https://doi.org/10.1017/jfm.2022.233
Public URL https://durham-repository.worktribe.com/output/3806437