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Forced Plumes in Uniformly Stratified Environment

  • Author / Creator
    Richards-Thomas, Tamar S
  • This research investigates radially spreading intrusion created from a forced plume, when fluid continuously injected vertically from a nozzle entrains uniformly stratified ambient as it falls back upon itself. The flow evolution is determined as it depends upon the ambient buoyancy frequency, $N$, the source momentum and buoyancy fluxes, $M_0$ and $F_0$, respectively. A turbulent forced plume falls to maximum depth, $\Zm$, rises back upon itself as a fountain to its neutral buoyancy depth, $\Zs$, then spreads radially outwards. Through theory and experiments we determine that $\Zs=f(\sigma) \Hp$, in which $\Hp= M0^(3/4) F0^(-1/2)$, $\sigma = (M0 N/F0)^2$, and $\ (sigma) propto \sigma^(-3/8)$ for $\sigma \lesssim 50$ and $f(\sigma) \propto \sigma^{-1/4}$ for $\sigma \gtrsim 50$ respectively. In the inertia-buoyancy regime the intrusion front advances in time as $\Rs \propto t^(3/4)$,consistent with models assuming a constant buoyancy flux into the intrusion where the intrusion first forms at radius, $R_1$, with thickness, $h_1$, constant in time. The intrusion thickness, $h(r,t)$, adopted a self-similar shape of the form $h/h_1 \simeq [(\Rs-r)/(\Rs-R_1)]^p$, with $p\simeq 0.55\ \pm 0.03$. From dense descending plumes in uniformly stratified ambient, we conveniently applied our results to supervolcanoes penetrating and spreading in the stratosphere.

  • Subjects / Keywords
  • Graduation date
    2014-11
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R3PV6BG0C
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Master's
  • Department
    • Department of Earth and Atmospheric Sciences
  • Supervisor / co-supervisor and their department(s)
    • Bruce R. Sutherland
  • Examining committee members and their departments
    • Gerhard Reuter (Earth and Atmospheric Science)
    • John Wilson (Earth and Atmospheric Science)
    • Morris Flynn (Mechanical Engineering)
    • Bruce R. Sutherland (Physics & Earth and Atmospheric Science)