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, $M0$ and $F0$, 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, $R1$, with thickness, $h1$, constant in time. The intrusion thickness, $h(r,t)$, adopted a self-similar shape of the form $h/h1 \simeq [(\Rs-r)/(\Rs-R1)]^p$, 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

  • Stratified
  • Environments
  • Forced Plumes

• Graduation date

  Fall 2014

• 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.