Experimental Investigation of the Pressure Distribution beneath a Floating Ice Block
Publication: Journal of Hydraulic Engineering
Volume 137, Issue 4
Abstract
Discrete ice floes approaching an ice cover from upstream will contribute to the lengthening of the cover or will become entrained in the flow. Currently, ice process models rely on empirical relationships to predict the behavior of ice floes at the leading edge of an intact ice cover. Knowledge of the hydrodynamic forces acting on individual ice floes is an important component of any model attempting to predict ice-cover progression. Experimental studies were conducted in a recirculating flume in the T. Blench Hydraulics Laboratory at the University of Alberta to increase the knowledge of the physical behavior of ice floes in water and the hydrodynamic forces that act on them. A hollow Plexiglas acrylic ice block outfitted with pressure taps was constructed to facilitate measurements of the pressure distribution beneath an ice block. The dynamic pressure was measured under the block for various block thickness-to-depth ratios and flow velocities. The dynamic pressure was found to decrease for increasing block thickness-to-approach flow depth ratios and increasing flow rates. A block with a rounded leading edge was also tested, and it showed a significantly reduced leading-edge pressure effect. The rectangular ice block results were categorized into separate effects: a pressure reduction attributable to Venturi effects and a pressure reduction attributable to leading-edge effects. A predictive relationship was developed for the pressure distribution beneath a floating ice block and the subsequent submerging force and underturning moment.
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Acknowledgments
This research is supported by scholarships to the first writer from the Natural Sciences and Engineering Research Council of Canada (NSERC) NSERCand Alberta Ingenuity and by NSERC research grants to the other two writers. This support is gratefully acknowledged.
The writers thank Perry Fedun and Chris Krath for their assistance with developing the experimental setup and Dr. Mark Loewen for his advice on these experiments. The writers also thank undergraduate students Brett Howard and Kimberly Alcorn for their assistance in the lab.
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© 2011 American Society of Civil Engineers.
History
Received: Jun 23, 2009
Accepted: Aug 23, 2010
Published online: Sep 4, 2010
Published in print: Apr 1, 2011
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