Experimental study of the bubble sweep-down phenomenon on three bow designs

The bubble sweep-down phenomenon around the oceanographic research vessels generates acoustic perturbations. A specific experimental protocol has been developed in a wave and circulating tank to study this phenomenon. This protocol is used to carry out trials on three different ship models in order to study the influence of the bow geometry on the bubble generation. For different test configurations, bubble clouds are described and compared in terms of area, maximal depth and vertical velocity to highlight bubble cloud dynamics surrounding the three ship models. The relation between the hydrodynamic flow field and the bubble generation is studied by means of Particle Image Velocimetry (PIV) measurements to study the phenomenon by the use of phase averaged velocity fields. The overall results enable us to characterize the bubble sweep-down phenomenon from the air bubble generation and propagation to the frequency of occurrence and the clouds behaviour.