Document Detail

Role of air in granular jet formation.
MedLine Citation:
PMID:  17678191     Owner:  NLM     Status:  MEDLINE    
A steel ball impacting on a bed of very loose, fine sand results in a surprisingly vigorous jet which shoots up from the surface of the sand [D. Lohse, Phys. Rev. Lett. 93, 198003 (2004)10.1103/PhysRevLett.93.198003]. When the ambient pressure p is reduced, the jet is found to be less vigorous [R. Royer, Nature Phys. 1, 164 (2005)10.1038/nphys175]. In this Letter we show that p also affects the rate of penetration of the ball: Higher pressure increases the rate of penetration, which makes the cavity created by the ball close deeper into the sand bed, where the hydrostatic pressure is stronger, thereby producing a more energetic collapse and jetting. The origin of the deeper penetration under normal ambient pressure is found to lie in the extra sand fluidization caused by the air flow induced by the falling ball.
Gabriel Caballero; Raymond Bergmann; Devaraj van der Meer; Andrea Prosperetti; Detlef Lohse
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-07-06
Journal Detail:
Title:  Physical review letters     Volume:  99     ISSN:  0031-9007     ISO Abbreviation:  Phys. Rev. Lett.     Publication Date:  2007 Jul 
Date Detail:
Created Date:  2007-08-06     Completed Date:  2008-01-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0401141     Medline TA:  Phys Rev Lett     Country:  United States    
Other Details:
Languages:  eng     Pagination:  018001     Citation Subset:  IM    
Faculty of Science and J.M. Burgers Centre for Fluid Dynamics, University of Twente, Enschede, The Netherlands.
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MeSH Terms
Silicon Dioxide*
Time Factors
Reg. No./Substance:
12597-69-2/Steel; 7631-86-9/Silicon Dioxide

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