Author(s): Vaclav Matousek
Linked Author(s): Vaclav Matousek
Keywords: No Keywords
Abstract: One of the modes of river freeze-up is the spreading of border ice towards the middle of the river. Experiments carried out in a hydraulic field laboratory showed that the velocity of border ice spreading towards the centre of the river is controlled by many factors. Freezing-up experiments were performed in a wooden heat-insulated flume of rectangular cross-section 0.7 x 0.35 m and 30 length. The water was led into the flume directly from the river without any treatment. The experiments were carried out under various water velocities and various values of heat flux from water surface to atmosphere, q, for which calm weather was required. From the obtained results the relation for the border ice spreading rate was derived. The relation derived from the model experiments is converted to a general form using the theory of similarity. The relation derived for the border ice speading rate serves as one of the conditions for ice cover iniciation due to border ice spreading. However, for the formation of border ice supercooling of the water surface is necessary. If the water temperature is more than 0C, it is essential that the flowing water does not dissolve the forming border ice. The mathematical formulation of these additional conditions is presented in the paper too.
Year: 1990