Underwater sound produced by individual drop impacts and rainfall

Hugh C. Pumphrey; L. A. Crum; L. Bjo/rno/

doi:10.1121/1.397353

Underwater sound produced by individual drop impacts and rainfall

The Journal of the Acoustical Society of America ◽

10.1121/1.397353 ◽

1989 ◽

Vol 85 (4) ◽

pp. 1518-1526 ◽

Cited By ~ 97

Author(s):

Hugh C. Pumphrey ◽

L. A. Crum ◽

L. Bjo/rno/

Keyword(s):

Underwater Sound ◽

Individual Drop ◽

Drop Impacts

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The entrainment of bubbles by drop impacts

Journal of Fluid Mechanics ◽

10.1017/s0022112090003378 ◽

1990 ◽

Vol 220 ◽

pp. 539-567 ◽

Cited By ~ 117

Author(s):

Hugh C. Pumphrey ◽

Paul A. Elmore

Keyword(s):

Water Surface ◽

Capillary Waves ◽

Experimental Results ◽

Single Bubble ◽

Underwater Sound ◽

The Third ◽

Entrainment Process ◽

Drop Impacts ◽

The Impact ◽

Small Bubbles

Various processes are described by which a drop of water, impacting on a water surface, may entrain a bubble. There are: (i) irregular entrainment, in which the complex details of a splash entrain bubbles; (ii) regular entrainment, in which the crater formed by the drop impact develops in a predictable way to form a single bubble; (iii) entrainment of large bubbles, in which most of the volume of the crater is trapped as a bubble; and (iv) Mesler entrainment, in which many very small bubbles are trapped in the very early stages of the impact process; possibly between wave crests of capillary waves which develop on the drop and on the water surface. This last process is different from the preceding three in that it produces very little sound. All of the processes except the third one have been described individually in the literature; here we present them together for comparison. The regular entrainment process is discussed in the greatest detail and some new experimental results are presented which concern the size and nature of the entrained bubbles. The significance of the regular and irregular entrainment processes to the generation of underwater sound by rain is discussed.

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Effects of flow velocity variation on rain driven transportation and the role of rain impact in the movement of solids

Soil Research ◽

10.1071/sr9880443 ◽

1988 ◽

Vol 26 (3) ◽

pp. 443 ◽

Cited By ~ 38

Author(s):

AJ Moss

Keyword(s):

Flow Velocity ◽

Water Erosion ◽

Velocity Variation ◽

Constant Intensity ◽

Modes Of Operation ◽

Direct Dependence ◽

Individual Drop ◽

Drop Impacts

Rain-flow transportation in, and airsplash from, shallow sheet flows of varying velocity were investigated experimentally by using four drop sizes at constant intensity (64 mm h-1). Whereas airsplash yields were negligible, rain-flow transportation reached rates of up to 3 g m-1s-1 and exhibited two distinct modes of operation, or regimes, depending on whether the unimpacted flows were laminar or transitional to turbulent. In the first of these regimes, clouds of particles, suspended by individual drop impacts, were moved downstream before settling back to the bed. In the second regime, general turbulence, imposed by drop bombardment, made the flow everywhere able to entrain and transport particles without direct dependence on individual drop impacts. These findings are combined with those of previous studies to make an assessment of the roles of rain and flow in water erosion.

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Experiment of Underwater Acoustic Produced by Single Drop Impacts

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.226-228.2137 ◽

2012 ◽

Vol 226-228 ◽

pp. 2137-2142

Author(s):

Zhao Ran Meng ◽

Wei Qiang Zhang ◽

Hui Sun

Keyword(s):

Acoustic Radiation ◽

Free Fall ◽

Underwater Sound ◽

Single Drop ◽

Wind Speeds ◽

Pressure Time ◽

Bubble Entrainment ◽

Time Trace ◽

Different Depths ◽

Drop Impacts

An experimental study of the underwater sound produced by single drop impacts influenced by different wind speeds, free fall heights and drop sizes at different depths is described in this article. Three kinds of acoustic radiation named impact sound, irregular bubble sound and delay bubble sound are distinguished by the pressure time trace. The images of bubbles taken near the point where the drop falls into water are shown. Some statistics laws of initial impact sound and irregular bubble sound affected by different condition included wind levels, heights of free fall and drop sizes are concluded. The directionality of initial impact sound is measured with wind and no wind. The process of delay bubble entrainment is analyzed and the measurements of bubble excitation probability in different condition are listed.

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