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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.

Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/5109 |

Date | 24 January 2012 |

Creators | Unduche, Fisaha Solomon |

Contributors | Dr. 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 Sets | University of Manitoba Canada |

Detected Language | English |

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