Underwater noise caused by precipitation

Bubble entrainment by the impact of drops on liquid surfaces

“…Hence if, as experiment suggests (Pumphrey & Crum 1988;Pumphrey et al 1989), only bubble-entrapping drops contribute to the underwater noise of rain, one would expect this noise to exhibit a peak a t a rather well-defined frequency, corresponding to the natural frequency of the entrained bubbles. This is precisely what is observed experimentally (Scrimger 1985;Scrimger et al 1987 ;Scrimger, Evans & Lee 1989;Prosperetti et al 1989), with the peak around 14-15 kHz. While we shall present detailed calculations lending further support to this hypothesis in a separate publication, we remark here that our computations estimate the radii of the bubbles entrained by drops to be between 0.19 and 0.30 mm.…”

The Freely-oscillating Bubble

“…Scrimger [110] and Nystuen [99] made the observation, which has since been confirmed [111,112]. Nystuen and Farmer [99, 100] made predictions of the shape of the initial short acoustic pulse, and nonacoustic dynamic pressure resulting from the flow field, through numerical modelling of the drop splash flow field.…”

Do we understand the bubble formation by a single drop impacting upon liquid surface?

“…[http://dx.doi.org/10.1063/1.4822483] Aeration of liquid by air entrainment is an important feature in a variety of natural phenomena and industrial applications, such as underwater acoustics, [1][2][3][4] aquatic life, 5 and environmental 6 and chemical 7 processes. Unfortunately, many aeration processes are generally unrepeatable due to the complex and highly interactive relationship of time-varying parameters.…”