Spontaneous generation of a swirling plume in a stratified ambient

Francisco Marques, Juan Lopez

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The transition from laminar to complex spatio-temporal dynamics of plumes due to a localized buoyancy source is studied numerically. Several experiments have reported that this transition is sensitive to external perturbations. Therefore, a well-controlled set-up has been chosen for our numerical study, consisting of a localized heat source at the bottom of an enclosed cylinder whose sidewall is maintained at a fixed temperature which varies linearly up the wall. Restricting the dynamics to the axisymmetric subspace, the first instability is to a puffing state. However, for smaller Grashof numbers, the plume becomes unstable to three-dimensional perturbations and a swirling plume spontaneously appears. The next bifurcation, viewed in the rotating frame where the plume is stationary, also exhibits puffing and suggests a connection between the unstable axisymmetric puffing solution and the swirling plume. Further bifurcations result in quasi-periodic states with a very low-frequency modulation, and these eventually become spatio-temporally complex.

Original languageEnglish (US)
Pages (from-to)443-463
Number of pages21
JournalJournal of Fluid Mechanics
Volume761
DOIs
StatePublished - Dec 25 2014

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Keywords

  • nonlinear instability
  • plumes/thermals
  • stratified flows

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Condensed Matter Physics

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