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A Theoretical and Experimental Study of the Evolution of Surface Ice

The theory of the formation of surface ice is not fully understood, yet its presence on water
surface affects the operation of many different kinds of hydraulic structures. It is known that
when the water surface temperature reaches supercooling ice particles are formed at the water
surface. If the intensity of turbulence is low these ice particles will be suspended on the
surface forming a surface ice. Herein, an experimental study that incorporates the effect of
depth, velocity, roughness and air temperature is carried out in a counter-rotating flume to
investigate the formation of surface ice in relation to these parameters. The experimental
result is supported by a mathematical model based on the theory of formation of surface ice.

A mathematical model is developed based on a comprehensive theory and is solved using
Matlab. The mathematical model integrates the effect of the heat balance on the water surface
with the degree of turbulent mixing and the rate of growth of surface ice. The two calibrating
parameters for the model are the magnitude of the initial seeding and the surface heat loss
coefficient. The developed mathematical model is calibrated for the different types of surface
ice formations for the data obtained from the experiment.

The experimental analysis shows that there are four main types of surface ice formations and
their formation is mainly dependent on the degree of turbulence. It is also found that the
types of these ice formations are dependent on the minimum supercooling temperature at an
average depth. Moreover, it is demonstrated that skim ice particles are those ice particles that
nucleate on the water surface during low to medium turbulent intensities and can have four
different types of shapes, namely needle shapes, finger shapes, hexagonal shapes and
irregular shapes. The sizes and relative quantities of these ice particles on the water surface
are also dependent on the degree of turbulence.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:MWU.1993/5109
Date24 January 2012
CreatorsUnduche, Fisaha Solomon
ContributorsDr. J.C. Doering, Engineering Department, Faculty of Engineering, Dr. P. Rasmussen, Engineering Department, Faculty of Engineering; Dr. R.W. Carson, Adjunct Professor, Civil Engineering Department, Faculty of Engineering; Dr. M. Tachie, Associate Head, Graduate Studies, Department of Mechanical and Manufacturing Engineering
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
Detected LanguageEnglish

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