English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This paper presents our investigation into the modification of a finite-widthinternal gravity wave beam arising from triadic resonance instability. Wepresent both experimental and weakly non-linear modelling to examine thisinstability mechanism, in which a primary wave beam generates two secondarywave beams of lower frequencies and shorter length scales. Through a versatileexperimental set-up, we examine how this instability develops over hundreds ofbuoyancy periods. Unlike predictions from previous zero-dimensional weaklynon-linear theory, we find that the approach to a saturated equilibrium statefor the triadic interactions is not monotonic; rather, the amplitudes andstructures of the constituent beams continue to modulate without ever reachinga steady equilibrium. To understand this behaviour we develop a weaklynon-linear approach to account for the spatio-temporal evolution of theamplitudes and structures of the beams over slow time-scales and longdistances, and explore the consequences using a numerical scheme. Through thisapproach, we establish that the evolution of the instability is remarkablysensitive to the spatio-temporal triadic configuration for the system and howpart of the observed modulations can be attributed to a competition between thelinear growth rate of the secondary wave beams and the finite residence time ofthe triadic perturbations within the underlying primary beam.

The long view of triadic resonance instability in finite-width internal gravity wave beams