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Forced Plumes in Uniformly Stratified Environment Open Access

Descriptions

Other title
Subject/Keyword

Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Richards-Thomas, Tamar S
Supervisor and department
Bruce R. Sutherland
Examining committee member and department
Gerhard Reuter (Earth and Atmospheric Science)
Morris Flynn (Mechanical Engineering)
Bruce R. Sutherland (Physics & Earth and Atmospheric Science)
John Wilson (Earth and Atmospheric Science)
Department
Department of Earth and Atmospheric Sciences
Specialization

Date accepted
2014-05-02T13:49:11Z
2014-11
Degree
Master of Science
Degree level
Master's
Abstract
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 $\f(sigma) propto \sigma^(-3/8)$ 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.
Language
English
DOI
doi:10.7939/R3PV6BG0C
Rights
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. 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.
Citation for previous publication
Richards T. S., Q. Aubroug, and B. R. Sutherland (2014), Radial intrusions from turbulent plumes in uniform stratification, Phys. Fuilds, 26, 036,602-1-036,602-17