Characteristics of sound radiation from large raindrops

Snyder, David; Jacobus, Peter W.; Medwin, Herman; Nystuen, Jeffrey A.

doi:10.1121/1.2028947

Cited by 4 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Theoretical curves for terminal speed were given by Pruppacher and Klett (1978). Snyder (1990) has verified that for these drops of equivalent diameter 2.2 to 4.6 mm the terminal speed Vr is described by Vr--4.6x/O.…”

Section: Rainfall Rates and Drop Size Distributionsmentioning

confidence: 95%

“…The Naval Postgraduate School has a unique facility for raindrop sound research: a 3-X 3-X26-m vertical utilities shaft with a 1.5-m deep X 1.5-m-diam anechoic tank at its bottom. The 26-m fall allows large drops ( ( 4.8 mm diameter) to reach terminal speeds at impact ( Snyder, 1990). This "drop tower" was used for all the large and mid-size drop experiments.…”

Section: A Physical Setupmentioning

confidence: 99%

See 1 more Smart Citation

The anatomy of underwater rain noise

Medwin¹,

Nystuen²,

Jacobus³

et al. 1992

The Journal of the Acoustical Society of America

Self Cite

108

View full text Add to dashboard Cite

When rain falls onto a large body of water it produces dominating underwater sound over a broad range of audio frequencies. Laboratory studies using more than 1000 single drops, covering the complete size range of actual rain drops at their terminal speeds, have now shown that the complete underwater spectrum of rainfall sound can be dissected into the impact and microbubble sounds produced by four acoustically distinctive ranges of drop diameters D. These are defined as "minuscule" drops (D<0.8 mm), "small" drops (0.8 mm• 2.2 mm). A minuscule raindrop produces only a very weak, almost undetectable, short duration impact noise. A small drop at terminal speed and at local, near-normal incidence, radiates measurable broadband impact sound followed by the very much stronger sound of a "type I" damped microbubble oscillating at frequencies near 15 kHz. A mid-size raindrop radiates only impact sound. Large raindrops, which comprise the major volume of moderate to heavy rainfall, produce an impact sound and a dominating, "type II," "primary" oscillating microbubble of characteristic frequency 2 to 10 kHz depending on the drop diameter. Also, large drops often generate weaker sounds from "secondary" bubbles. The average acoustic energy spectra of large raindrops are distinctive functions of their diameters, the salinity of the surface water, and the temperature difference between the drop and the surface water. When the underwater acoustic intensity spectrum during heavy rain is calculated from the single drop acoustic energy spectra and the drop size distribution, it compares quite well with ocean measurements. The gas injection at the airwater interface is calculated from the probability of bubble formation during a heavy rainfall.

show abstract

Section: Rainfall Rates and Drop Size Distributionsmentioning

confidence: 95%

Section: A Physical Setupmentioning

confidence: 99%

The anatomy of underwater rain noise

Medwin¹,

Nystuen²,

Jacobus³

et al. 1992

The Journal of the Acoustical Society of America

Self Cite

108

View full text Add to dashboard Cite

show abstract

“…Briefly, the growth and collapse of the crater was studied experimentally and modelled by Engel (1966Engel ( , 1967, van de Sande et al (1974) and Bisighini et al (2010). Others mention high-energy impacts in passing (Hallet & Christensen 1984) or focus on other aspects, such as sound radiation (Franz 1959;Snyder 1990) or coronal discharge (Khaleeq-ur-Rahman & Saunders 1988). Raindrops greater than 2.56 mm in diameter falling on a water surface at terminal speed will fall in the BC regime.…”

mentioning

confidence: 99%

Splash behaviour and oily marine aerosol production by raindrops impacting oil slicks

Murphy

d’Albignac

et al. 2015

J. Fluid Mech.

View full text Add to dashboard Cite

The high-speed impact of a droplet on a bulk fluid at high Weber number (We) is not well understood but is relevant to the production of marine aerosol by raindrop impact on the sea surface. These splashes produce a subsurface cavity and a crown which closes into a bubble canopy, but a floating layer of immiscible oil, such as a crude oil slick, alters the splash dynamics. The effects of oil layer fluid properties and thickness, droplet size and impact speed are examined by high-speed visualization. Oil layer rupture and crown behaviour are classified by dimensional scaling. The subsurface cavity volume for impact on thick layers is shown to depend on the Reynolds number (Re), although canopy formation at high Re introduces a competing We effect since rapid canopy closure is found to retard cavity expansion. Time-resolved kinematic measurements show that thin crude oil slicks similarly alter crown closure and cavity growth. The size and spatial distributions of airborne droplets are examined using high-speed holographic microscopy. The droplets have a bimodal distribution with peaks at 50 and 225 µm and are clustered by size at different elevation angles. Small droplets (50 µm) are ejected primarily at shallow angles, indicating production by splashing within the first 100 µs and by breakup of microligaments. Larger droplets (225 µm) are found at steeper elevation angles, indicating later production by capillary instability acting on large ligaments protruding upward from the crown. Intermittent droplet release while the ligaments grow and sweep upward is thought to contribute to the size-dependent spatial ordering. Greater numbers of small droplets are produced at high elevation angles when a crude oil layer is present, indicating satellite droplet formation from ligament breakup. A crude oil layer also increases the target fluid Ohnesorge number, leading to creation of an intact ejecta sheet, which then ruptures to form aerosolized oil droplets.

show abstract

“…where w r is the terminal velocity of drops in the air (see Snyder (1990)). The terminal velocity is computed following the third order polynomial estimates of Dingle and Lee (1972).…”

Section: Rain Distributionmentioning

confidence: 99%

The Impact of Entrained Air on Wave Dissipation

Restrepo

Ayet

Cavaleri

2020

Preprint

View full text Add to dashboard Cite

Abstract. We make a physical-mathematical analysis of the implications that the presence of a large number of tiny bubbles may have on the thin upper layer of the sea. In our oceanographic example the bubbles are due to an intense rain on an otherwise non-stormy surface; if stormy, other processes would take the role. For the direct effect we have analyzed, the implications are estimated non-significant when compared to other processes of the ocean. However, we hint to the possibility that our analysis may be useful in other areas of research or practical application.

show abstract

Characteristics of sound radiation from large raindrops

Cited by 4 publications

References 0 publications

The anatomy of underwater rain noise

The anatomy of underwater rain noise

Splash behaviour and oily marine aerosol production by raindrops impacting oil slicks

The Impact of Entrained Air on Wave Dissipation

Contact Info

Product

Resources

About