Effects of rotation on turbulent buoyant plumes in stratified environments

Alexandre Fabregat Tomàs, Andrew C. Poje, Tamay M Ozgokmen, William K. Dewar

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We numerically investigate the effects of rotation on the turbulent dynamics of thermally driven buoyant plumes in stratified environments at the large Rossby numbers characteristic of deep oceanic releases. When compared to nonrotating environments, rotating plumes are distinguished by a significant decrease in vertical buoyancy and momentum fluxes leading to lower and thicker neutrally buoyant intrusion layers. The primary dynamic effect of background rotation is the concentration of entraining fluid into a strong cyclonic flow at the base of the plume resulting in cyclogeostrophic balance in the radial momentum equation. The structure of this cyclogeostrophic balance moving upward from the well head is associated with a net adverse vertical pressure gradient producing an inverted hydrostatic balance in the mean vertical momentum budgets. The present simulations reveal that the primary response to the adverse pressure gradient is an off-axis deflection of the plume that evolves into a robust, organized anticyclonic radial precession about the buoyancy source. The off-axis evolution is responsible for the weaker inertial overshoots, the increased thickness of lateral intrusion layers, and the overall decrease in the vertical extent of rotating plumes at intermediate Rossby numbers compared to the nonrotating case. For inlet buoyancy forcings and environmental Rossby numbers consistent with those expected in deepwater blowout plumes, the speed of the organized precession is found to be as large as typical oceanic cross-flow speeds.

Original languageEnglish (US)
Pages (from-to)5397-5417
Number of pages21
JournalJournal of Geophysical Research: Oceans
Volume121
Issue number8
DOIs
StatePublished - Aug 1 2016

Keywords

  • buoyant plumes
  • deepwater releases
  • rotation
  • stratified flows
  • turbulence

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Ecology
  • Aquatic Science
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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