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

Faimon, Jiřı́; Lang, Marek

doi:10.5038/1827-806x.42.2.3

Cited by 29 publications

(27 citation statements)

References 9 publications

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“…(5), the total volumetric airflow in the cave chamber consists of two different components: (i) natural airflow (v N ) nad (ii) anthropogenic airflow (v A ). whereas the external temperature is considered to be the driving force of natural cave airflow (de Freitas et al 1982;Christoforou et al 1996;Buecher 1999;Jernigan & Swift 2001;Pflitsch & Piasecki 2003;Russell & MacLean 2008;Kowalczk & Froelich 2010;Faimon & Lang 2013), the visitor movement inside the cave is the driving force for the anthropogenically induced airflow. The visitor group may represent a piston pushing ahead the air in cave corridor.…”

Section: Influence Of Visitor Movementmentioning

confidence: 99%

“…2c). The positive values of ΔT correspond to downward airflows (DAF ventilation mode) and the negative values correspond to upward airflows (UAF ventilation mode) (Faimon et al, 2012a;Faimon & Lang, 2013). During DAF mode, the CO 2 concentrations increased: the maxima of CO 2 concentrations reached up to 4.00 × 10 -2 mol m -3 (930 ppmv) and 3.45 × 10 -2 mol m -3 (800 ppmv) in the first and second period of DAF mode, respectively.…”

Section: Datamentioning

confidence: 99%

“…Since density is particularly a function of temperature, cave airflows are mostly related to the temperature difference, DT = T exterior -T cave [°C], where T exterior is external air temperature and T cave is cave air temperature (Christoforou et al 1996;Pflitsch & Piasecki 2003;Russell & MacLean 2008;Kowalczk & Froelich 2010;Faimon & Lang 2013). Based on the sign of the temperature difference, two ventilation regimes are distinguished.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A case study of anthropogenic impact on the CO2 levels in low-volume profile of the Balcarka Cave (Moravian Karst, Czech Republic)

Lang¹,

Faimon²,

Ek³

2015

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IzvlečekAnthropogenic impact on CO 2 levels was studied in the lowvolume chamber connected with the low-profile corridor in Balcarka Cave, the show cave in Moravian Karst, during the period of limited ventilation. Modeling showed that the natural CO 2 levels were controlled by the CO 2 fluxes (up to ~ 3.14 × 10 -2 mol s ) by factor of more than 60. These airflows caused cave ventilation mode's switching and, significant drop of CO 2 fluxes/levels due to changed ventilation. The study therefore indicates that various anthropogenic influences in show cave can balance and neutralize each other, in dependence on cave morphology and seasonal conditions.

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Section: Influence Of Visitor Movementmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A case study of anthropogenic impact on the CO2 levels in low-volume profile of the Balcarka Cave (Moravian Karst, Czech Republic)

Lang¹,

Faimon²,

Ek³

2015

Self Cite

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“…In this section, we use a basic air circulation model for caves with an active hearth to estimate the smoke levels that early humans might have been exposed to in different areas of the cave (Cigna 1968;De Freitas et al 1982;Faimon & Lang 2013;McGrattan et al 2017). This model can be used for cave structures as it was verified in a quarry test simulating Chauvet-Pont-d'Arc Cave (Lancanette et al 2017).…”

Section: Methodsmentioning

confidence: 99%

The Significance of Air Circulation and Hearth Location at Paleolithic Cave Sites

Kedar

Barkai

2019

Open Quaternary

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Hearths were constructed and used at Paleolithic cave and rockshelter sites in Africa, Europe and Asia as early as the late Lower Paleolithic period. The advantages of the use of fire have been widely researched for the last decades. However, only a few studies have focused on the possible negative impact of the use of fire within closed spaces, such as caves. One of the major negative fire products is smoke, which has an immediate, as well as long-term, effect on humans and may even prevent cave occupation after a short period. In this study we propose a basic air circulation model based on thermodynamics to represent smoke ventilation in caves. We employ this model to shed light on the relationship between smoke dispersal and cave structure, opening dimensions, hearth characteristics, and seasonal temperature fluctuations. We further show that hearth location was crucial in allowing humans to occupy prehistoric caves while using fire on a regular basis. We present preliminary insights from specific case studies, demonstrating the potential of understanding smoke ventilation in reconstructing the hearth season of use and location within the cave.

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“…INVERSION A large consensus exists stating that driving forces of airflow are proportional to the differences in air densities (Cigna 2002;De Freitas et al 1982;Spötl et al 2005;Faimon et al 2012;Faimon & Lang 2013;Borsato et al 2015).…”

Section: Driving Force Of the Airflowmentioning

confidence: 99%

Evidence of daily and seasonal inversions of airflow in Petites Dales cave, Normandy, France

Masséi¹,

Magne²,

Rodet³

et al. 2017

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-Pierre Viard: Dnevni in sezonski obrati smeri zračnega toka v jami Petites Dales, Normandija, Francija V članku poročamo o podrobni mikroklimatski študiji v jami Petites Dales. V jami z enim samim vhodom smo dve leti opazovali temperaturo, vlago in porazdelitev zračnih tokov. Podrobne dnevne meritve temperature in zračnega toka kažejo na stratifikacijo in dnevni obrat smeri toka. Poleti zunanji zrak vdira v jamo pri stropu, pozimi pa pri tleh. Pri tem se pri vhodu oblikuje profil hitrosti zraka v obliki črke S, globlje v jami pa konvekcijska zanka. V vmesnih obdobjih lahko pride do preklapljanja iz dotoka pod stropom v dotok pri dnu in obratno, kar v članku obravnavamo z vidika termodinamike. V tej raziskavi smo prvič pojasnili dnevne obrate smeri zraka v primerljivih jamah. Študije jamske mikroklime so pomembne za razumevanje jamskega ekosistema, procesov v jamah ter človekovega vpliva nanje. Ključne besede: jama, mikroklima, kras, zračni tok, temperatura, spremenljivost. -entrance is presented in this paper. Two years of cave monitoring investigate temperature, weight of water vapour and airflow distributions outside and inside the cavity to determine the global behaviour of the karst cave. In addition, daily measurements of temperature and airflow demonstrate clearly the stratification of the air and inversions of the airflow during day-time. The cave air is intensively exchanged with external air during the years, with two main modes: (i) airflow enters from the ceiling during summer period and (ii) airflow enters from the floor during winter. At the entrance, an Sshaped velocity profile was observed and far from the entrance, convection loops were observed. During the other period of the year, the airflows may switch from top to bottom or conversely. The thermodynamic conditions of switching are discussed in this paper. This study provided for the first time evidence of daily airflow inversion. Study of cave climates is required in the comprehension of cave flora and fauna, thermodynamic conditions for karst processes underground, hydrogeological features of speleothems, human impact when caves are visited.

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

Cited by 29 publications

References 9 publications

A case study of anthropogenic impact on the CO2 levels in low-volume profile of the Balcarka Cave (Moravian Karst, Czech Republic)

A case study of anthropogenic impact on the CO2 levels in low-volume profile of the Balcarka Cave (Moravian Karst, Czech Republic)

The Significance of Air Circulation and Hearth Location at Paleolithic Cave Sites

Evidence of daily and seasonal inversions of airflow in Petites Dales cave, Normandy, France

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