Accession Number : ADA260842


Title :   Underwater Sound Radiation From Single Large Raindrops at Terminal Velocity; The Effects of a Sloped Water Surface at Impact


Descriptive Note : Master's thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA


Personal Author(s) : Miller, Sr, Glenn A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a260842.pdf


Report Date : Dec 1992


Pagination or Media Count : 51


Abstract : 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.


Descriptors :   *RAINDROPS , *BUBBLES , *UNDERWATER SOUND , *WATER JETS , VELOCITY , FREQUENCY , DENSITY , DIAMETERS , DROPS , OCEANS , FLUID DYNAMICS , GRAVITY WAVES , RAINFALL , SOUND , AEROSOLS , ACOUSTIC WAVES , ENERGY , THESES , SURFACES


Subject Categories : Acoustics
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE