Breaking wave bubble measurements around ship model by optical probe

The bubble sweep-down phenomenon around oceanographic research vessels generates acoustic disturbances. The phenomenon can be reproduced on a 1/30 scale ship model in a wave and current circulating flume tank taking into account ship motions. Optical probe can then be used to measure locally the size and the velocity of the bubbles generated by breaking waves. A comparison of the obtained results with more classical results obtained from bubble detection by image tracking is discussed. The two methods provide complementary results for bubble characteristics. However, bubble detection by optical probe has the advantage of knowing the bubble position in the three dimensions of space. The overall results of this paper provide new elements for the study and the understanding of the bubble sweep-down phenomenon in addition to previous 2D and 3D studies, where the dynamics of bubble clouds have been characterized.