Numerical Investigations of the Deposition of Unattached {sup 218}Po and {sup 212}Pb from Natural Convection Enclosure Flow

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We report numerical predictions of the deposition to enclosure surfaces of unattached {sup 218}Po and {sup 212}Pb, short-lived decay products of {sup 222}Rn and {sup 220}Rn, respectively. The simulations are conducted for square and rectangular two-dimensional enclosures under laminar natural convection flow with Grashof numbers in the range 7 x 10{sup 7} to 8 x 10{sup 10}. The predictions are based upon a finite-difference natural-convection fluid-mechanics model that has been extended to simulate the behavior of indoor radon decay products. In the absence of airborne particles, the deposition velocity averaged over the enclosure surface was found to be in the ... continued below

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Nazaroff, W.W.; Kong, D. & Gadgil, A.J. February 1, 1992.

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We report numerical predictions of the deposition to enclosure surfaces of unattached {sup 218}Po and {sup 212}Pb, short-lived decay products of {sup 222}Rn and {sup 220}Rn, respectively. The simulations are conducted for square and rectangular two-dimensional enclosures under laminar natural convection flow with Grashof numbers in the range 7 x 10{sup 7} to 8 x 10{sup 10}. The predictions are based upon a finite-difference natural-convection fluid-mechanics model that has been extended to simulate the behavior of indoor radon decay products. In the absence of airborne particles, the deposition velocity averaged over the enclosure surface was found to be in the range (2-4) x 10{sup -4} m s{sup -1} for {sup 218}Po and (1-3) x 10{sup -4} m s{sup -1} for {sup 212}Pb. In each simulation, the deposition rate varied by more than an order of magnitude around the surface of the enclosure with the largest rates occurring near corners. Attachment of decay products to airborne particles increased the deposition velocity; for example, attachment of {sup 218}Po at a rate of 50 h{sup -1} increased the predicted average deposition velocity by 30-70% over values in the absence of attachment. The simulation results have significance for assessing the health risk associated with indoor exposure to {sup 222}Rn and {sup 220}Rn decay products and for investigating the more general problem of the interaction of air pollutants with indoor surfaces.

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  • Journal Name: Journal of Aerosol Science; Journal Volume: 23; Journal Issue: 4

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  • Report No.: LBL-30249
  • Grant Number: DE-AC02-05CH11231
  • DOI: 10.1016/0021-8502(92)90003-E | External Link
  • Office of Scientific & Technical Information Report Number: 939272
  • Archival Resource Key: ark:/67531/metadc896812

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • February 1, 1992

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  • Sept. 27, 2016, 1:39 a.m.

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  • Jan. 4, 2017, 5:39 p.m.

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Nazaroff, W.W.; Kong, D. & Gadgil, A.J. Numerical Investigations of the Deposition of Unattached {sup 218}Po and {sup 212}Pb from Natural Convection Enclosure Flow, article, February 1, 1992; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc896812/: accessed November 25, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.