Underwater sound radiation from single large raindrops at terminal velocity: the effects of a sloped water surface at impact
Miller, Glenn A., Sr.
Nystuen, Jeffrey A.
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Previous studies have shown that terminal velocity raindrops striking a smooth water surface create oscillating bubbles that radiate significant underwater sound energy. Those studies identified two diameter ranges that produce bubbles: small drops (.8-1.1 mm diameter) which produce bubbles by one mechanism and large drops (2.2-4.6 mm diameter) which create bubbles by a different mechanism. Effects of oblique incidence have been studied only for small drops. Average energy spectra were calculated for a range of raindrop sizes striking a smooth water surface. This work deals with the real life situation of large raindrops of a size often present in heavy rainfall (4.6 mm diameter) striking a sloped water surface. Terminal velocity is used to simulate natural rainfall, and the sloped surface is used to simulate the surface gravity waves of a natural sea. The effects of a sloped water surface on frequency spectra and energy for 4.6 mm raindrops are estimated. By comparing energy spectra generated by single drops in an anechoic laboratory tank to underwater sound spectra measured at sea, it will be possible to estimate heavy rainfall rate by means of remote underwater listening devices.
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Kurgan, Armagan (Monterey, California. Naval Postgraduate School, 1989-12);The sound generated by rainfall at sea is caused by raindrops of a wide range of sizes and angles of incidence, which fall at their terminal velocities. The purpose of this laboratory research has been to make complete ...
Oscillating microbubbles created by water drops falling on fresh and salt water : amplitude, damping and the effects of temperature and salinity. Scofield, Christopher D. (Monterey, California. Naval Postgraduate School, 1992-06);Recent studies of underwater sound produced by raindrops have identified trapped bubbles as the principle sound source. Two mechanisms have been described, one for small drops (Type I) and one for large drops (Type II). ...
Jacobus, Peter W. (Monterey, California. Naval Postgraduate School, 1991-09);The principal underwater sound energy radiated by terminal velocity raindrops at sea is due micro-bubble entrainment and oscillations which occur for drops of the two diameter ranges 0.8 to 1.1 mm (Type I) and 2.2 to 4.6 ...