ABSTRACT
Brash ice channels are frequently created during ship navigation. To improve the understanding of the brash ice channel development experimental tests have been conducted. The tests were performed by repeated passage of a model ship in a ship channel. Channel profile measurements, temperature profiles, salinity of cores were taken from consolidated brash ice edges and centre of the channel, as well as measurements of the ship model parameters. The results provide insight into the processes in the brash ice channel during freezing and breaking. The paper presents an overview of the tests, measurements and results. The findings from these tests provide an improved understanding of the process in brash ice channel development which can be incorporated into modelling techniques for marine design and operations.
Brash ice can influence the icebreaking performance of ships and is also created during ice management operations impacting the performance and safety. This is outlined by Riska et al. (1997) and Liferov et al. (2018), amongst others. In this study we consider ‘brash ice’ to be small pieces of ice broken from repeated ship navigation in the same track, see Figure 1. Brash ice accumulations are also present in ports, channels and terminal areas which can impede operations if sufficient amounts are present, as described by Sandkvist (1986). There is, however, a need for understanding of brash ice growth processes for consolidation and thickness prediction. For example, the freezing of the ship channel edges is considered of importance, as these are difficult for icebreakers to break and also in making the channel width narrower.
The channel formation is described by Ettema and Huang (1990) and recent brash ice growth models, for example see Riska et al. (2019), include the cyclic ship breaking and refreezing process. The model is based on extension of earlier growth models which modify the Stefan type growth modelling. However these are 1D models and lateral motion of ice is not taken into account. Consequently, an improved physical comprehension is needed on the influence of the development of brash ice channels in order to improve the theoretical modelling of the brash ice processes.
