Gravity Currents Propagating Upslope in Uniform and Two-Layer Stratified Ambients

• Author / Creator

  Marleau, Larissa J

• Bottom propagating gravity currents resulting from full- and partial-depth lock-release experiments are investigated as they propagate up a rising slope in uniform and two-layer stratified ambients. In the case of uniform ambients, the gravity current front decelerates in a nearly uniform manner along the slope at a rate that agrees with theoretical predictions. The shape of the gravity current as it decelerates over relatively steep slopes is found to be self-similar with a nearly linear decrease of the head height between the start of the slope and up to 80\% of the distance to the nose. Some deviation from self-similar behaviour is found in cases with small slopes because of the comparatively large volume of fluid in the gravity current tail that flows downslope while the front continues to advance upwards. In the case of two-layer ambients, the initial gravity current front speed is found to be consistent with a theory adapted from \cite{shindalziellinden2004}. The subsequent evolution depends on the gravity current speed relative to the speed of the interfacial disturbance it creates. The deceleration of supercritical gravity currents, which travel faster than the interfacial disturbance, is gradual and agrees well with the relationship developed for upslope gravity currents in uniform density ambients and modified for a two-layer ambient. In most subcritical cases the gravity current suddenly comes to rest as a consequence of interactions with the interfacial disturbance. The disturbance amplitude, speed, and width are found to be nearly constant during its evolution. In cases for which the ambient interface intersected the tank bottom, the amplitude, speed, and width are nearly constant up to the point where the lower layer shallowed and the disturbance transformed into an upslope propagating gravity current.

• Subjects / Keywords

  • Gravity current
  • Stratified
  • Slope

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3Z60CD2H

• 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.