Analytical Model of Navigable Channel Evolution in Ice Conditions
- Evgeny B. Karulin (Krylov State Research Centre) | Marina M. Karulina (Krylov State Research Centre) | Oleg V. Tarovik (Krylov State Research Centre)
- Document ID
- International Society of Offshore and Polar Engineers
- International Journal of Offshore and Polar Engineering
- Publication Date
- September 2019
- Document Type
- Journal Paper
- 277 - 285
- 2019. The International Society of Offshore and Polar Engineers
- porosity, Ob Bay, Ice channel, brash ice, consolidation
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- 13 since 2007
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Ship traffic via navigable freezing ice channels causes a gradual accumulation of small ice floes mixed with water, known as brash ice. The thickness of the brash ice layer may reach the values when ship navigation becomes difficult or even impossible. This paper introduces a computational model intended to predict ice channel evolution in winter. The model considers the thermodynamics of the ice-growing process and allows the estimation of the parameters of the cross-section of the ice channel depending on the number of freezing degree-days and the schedule of ship passages. Unlike existing models, the described scheme of channel evolution takes into account that some brash ice is pushed beneath ice channel edges by passing vessels, and therefore the obtained cross-section profile is similar to that observed in full-scale conditions.
Ship navigation in freezing waters is conducted via ice channels made in the ice cover. A channel behind the icebreaker remains but is filled with broken ice fragments. Ships may use the same ice channel time and again. Between ship passages, a fresh ice cover grows in the channel under freezing temperatures. At each ship passage, the ice cover is broken again, and ice blocks are split into smaller pieces. Frequently used channels accumulate smaller ice floes (mean size 50 cm) mixed with water (“brash ice”). The water content is defined by the porosity of the brash ice, which influences the intensity of ice accumulation in the channel.
Ship navigation in ice channels filled with brash ice involves two main issues. First, it is necessary to know the current state of the ice channel. The second issue is related to ship performance in the ice channel, including the hull resistance and the effect of brash ice on propeller operation. This study examines only the first issue, the evolution of the ice channel during the winter season.
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