Field studies and numerical simulations of ice bustles on vertical piles

In cold climates, ice may accrete and form ice bustles on piles exposed to changes in water level. Ice bustle formation is related to cooling of the piles below the temperature of surrounding water when the heat conductivity of the pile material is higher than the heat conductivity of the water. In this case, the ice grows laterally from the surface of the pile at greater depths than the thickness of the ice at the surrounding level. High adhesion between the ice and pile keeps the bustles in place during water level changes and allows the bustles to develop over time. The vertical and horizontal dimension of ice bustles formed on cylindrical quay steel piles (Ø 0.8 m) in the Svea coal harbour, Spitsbergen, was about 1.5 m during the winter and spring of 2007 and 2008. The ice bustles had cylindrical shapes with slightly downward sloping side walls. Their top surface coincided with the water level at maximal tide, and they were nearly above the water surface at minimal tide. A mathematical model describing the formation of ice bustles around the cylindrical pile was developed using Comsol Multiphysics 3.3a. The ice bustle growth was simulated with a constant mean water level and takes into account tidal variations of the water level. The influence of meteorological conditions, time, and tidal amplitude on the ice bustle size is discussed.