Underwater sound radiation from single large raindrops at terminal velocity: the effects of a sloped water surface at impact

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.

Department dc:contributor.department

Engineering Acoustics Academic Committee

Grantor dc:publisher

Monterey, California. Naval Postgraduate School

Year dc:date.issued

1992

Author dc:creator

• Miller, Glenn A., Sr.

Advisors dc:contributor.advisor

• Medwin, Herman
• Nystuen, Jeffrey A.

Statement dc:rights

• This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/10945/24083

OAI identifier oai:identifier

oai:calhoun.nps.edu:10945/24083