Research on the mechanism and distribution characteristics of bubble generation in the bow of a research vessel

Abstract

The flow around the ship bow involves complex three-dimensional flow separation, leading to the generation of a large number of bubbles. These bubbles have a significant impact on acoustic instrumentation, and mitigating their effects has become a key focus in the field. Central to this issue is understanding the bubble generation mechanism near the bow. This study investigates the generation of bubbles in the bow region through a combination of physical experiments and numerical simulations. Experiments were conducted in a wind-wave-current circulating flume under controlled laboratory conditions. Qualitative observations of bubble phenomena near the bow were carried out, complemented by numerical simulations to examine the statistical characteristics of bubble distribution. Two distinct types of bubble generation were identified in the experiments: air entrainment due to vortex formation and bubble clouds caused by wave breaking. The former is primarily influenced by hull geometry and the turbulence intensity of the incoming flow, whereas the latter is strongly affected by wave parameters and hull motion. Numerical simulations successfully reproduced bubble generation around the hull, revealing vortex entrainment and wave-breaking-induced bubble clouds. The bubble size–density distribution follows a power-law behavior, with the slope of the bubble density versus diameter distribution found to be -3.3.