Wave Attenuation of Regular Waves Propagating through Frazil/Grease Ice and Pancake Ice

Abstract

This paper focuses on the part for studying an attenuation of surface waves propagating through frazil/grease ice and pancake ice in a wave tank in a cold room. The tank is equipped with a wave maker of plunger type. The air temperature is kept around -8 degrees during the whole experiment. Regular waves of eleven different frequencies are generated in during 50 sec to avoid the reflection waves. The portion of the wave signals before the arrival of reflections is used to measure the wave number and the attenuation rate. As a result, it is found that the wave attenuation decreases with increasing frequencies. For the incident wave of marginal ice zone, the attenuation rates of the high frequencies side become 70 %. Further, to estimate the wave attenuation in grease-pancake ice, it is necessary to consider not only frequency but also wave height.