Infrasonic Resonances in Natural Underground Cavities

Plummer, William T.

doi:10.1121/1.1911823

Cited by 12 publications

(11 citation statements)

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“…The modeling of driving forces showed that the reason of such weak airflows is the small difference between the levels of both cave entrances. The frequencies of airflow oscillations from 0.3 to 40 mHz are roughly in the range reported by Plummer (1969). Further details on cave airflow oscillations can be found in Faust (1947), Cigna (1968), or Faimon et al (2012.…”

Section: Discussionmentioning

confidence: 58%

Variances in airflows during different ventilation modes in a dynamic U-shaped cave

Faimon¹,

Lang²

2013

IJS

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Airflow dynamics were studied in Císařská Cave (Moravian Karst, Czech Republic) under different seasonal conditions. The dependence of airflows on the difference between external and cave temperatures is nonlinear and roughly obeys the Darcy-Weisbach equation. The upward airflows were found to be systematically higher than the downward airflows under comparable driving forces. The principle reason is nonlinearity between air temperature and air density. U-shaped cave geometry magnifies this effect by feedback between external temperature and airflow driving forces. Whereas this feedback is positive during the upward airflow ventilation mode, it is negative during the downward airflow mode. To discuss the behavior in detail, a simplified model based on balancing the masses of two equivalent air columns of different temperatures and densities is proposed. The results contribute to a better understanding of cave microclimate evolution, cave CO2 dynamics, and speleothem growth

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Section: Discussionmentioning

confidence: 58%

Variances in airflows during different ventilation modes in a dynamic U-shaped cave

Faimon¹,

Lang²

2013

IJS

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“…This work shows large values of standard deviation at low frequencies (63 Hz and 125 Hz) because in the underground locations there are low frequencies components (Plummer, 1969), while from the frequency of 250 Hz these differences are small. At the frequency of 1.0 kHz the value of the reverberation time (T 30 ) is about 1.0 s, while the value of the definition (D 50 ) is superior to 0.50.…”

Section: Discussionmentioning

confidence: 98%

The Acoustics of the Catacombs

Iannace¹,

Trematerra²,

Qandil³

2015

Archives of Acoustics

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The catacombs are underground places. This paper reports the results of acoustic measurements carried out inside the catacombs of "San Gennaro" (Naples) and in those one of "San Callisto" (Rome). Originally the catacombs were also used to perform sacred functions, although we don't know the type of these functions i.e. if they were spoken, sung or performed as psalms. This paper presents acoustic measurements carried out in catacombs using the impulse response method, and by the analysis of the monaural acoustic parameters, (T30, EDT, C80, D50 and STI), the authors intend to understand the type of religious ceremony performed in the catacombs. If the catacombs had been reverberant places, they could not have been used for prayers because the echoes would have created difficulties in concentration and meditation for the devotees due to the poor speech comprehension.

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“…Such anemometers would need to be able to measure wind speeds of <1 m/s. Given that the periodicity of the wind speeds is the most important consideration, Plummer (1969) used a small device on a tripod which measured the persistent wind direction (rather than wind speeds). Once the persistent wind direction reversed, the device recorded the time of reversal.…”

Section: Discussionmentioning

confidence: 99%

“…One terrestrial air-movement mechanism occurs when small pressure differences between the cave interior and the external atmosphere produce a type of Helmholtz resonance (Cigna, 1968;Plummer, 1969;Faimon et al, 2012). Note that such resonances are not to be confused with passing weather systems creating pressure gradients, a type of pressure forcing referred to hereafter as "synoptic".…”

Section: Introductionmentioning

confidence: 99%

“…For flat smooth plates under fully turbulent flow parallel to the plate, Cd/l = 0.005 is commonly used (e.g., Kundu & Cohen, 2004). Plummer (1969) analyzed three terrestrial cave configurations in order to detect Helmholtz resonances. His simplest cave configuration was a cavity of roughly 140,000 m 3 connected to the outside via a 360 m passageway.…”

Section: Introductionmentioning

confidence: 99%

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Martian cave air-movement via Helmholtz resonance

Williams¹,

Titus²,

Okubo³

et al. 2017

IJS

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Abstract:Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed.caves, resonance, Mars, wind, cave volume

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Infrasonic Resonances in Natural Underground Cavities

Cited by 12 publications

References 0 publications

Variances in airflows during different ventilation modes in a dynamic U-shaped cave

Variances in airflows during different ventilation modes in a dynamic U-shaped cave

The Acoustics of the Catacombs

Martian cave air-movement via Helmholtz resonance

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