Universität zu Köln

Shao, Yaping ORCID: 0000-0002-2041-5479 and Klose, Martina (2016). A note on the stochastic nature of particle cohesive force and implications to threshold friction velocity for aerodynamic dust entrainment. Aeolian Res., 22. S. 123 - 126. OXFORD: ELSEVIER SCI LTD. ISSN 2212-1684

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Abstract

There is considerable interest to determine the threshold for aeolian dust emission on Earth and Mars. Existing schemes for threshold friction velocity are all deterministic in nature, but observations show that in the dust particle size range the threshold friction velocity scatters strongly due to stochastic inter-particle cohesion. In the real world, there always exists a certain amount of free dust which can be easily lifted from the surface by weak winds or even turbulence, as exemplified by dust devils. It has been proposed in the dust-devil research community, that the pressure drop at dust-devil center may be a major mechanism for dust-devil dust emission, known as the zip effect. It is questioned here whether the zip effect is substantial or whether the elevated dust concentration in dust devils is due to free dust emission. A simple analysis indicates that the zip effect appears to be small and the dust in dust devils is probably due to free dust emission and dust convergence. To estimate free dust emission, it is useful to define a lower limit of dust-particle threshold friction velocity. A simple expression for this velocity is proposed by making assumptions to the median and variance of inter-particle cohesive force. The simple expression is fitted to the data of the Arizona State University Vortex Generator. While considerable uncertainty remains in the scheme, this note highlights the need for additional research on the stochastic nature of dust emission. (C) 2016 Published by Elsevier B.V.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Shao, Yaping UNSPECIFIED orcid.org/0000-0002-2041-5479 UNSPECIFIED Klose, Martina UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-263718
DOI:	10.1016/j.aeolia.2016.08.004
Journal or Publication Title:	Aeolian Res.
Volume:	22
Page Range:	S. 123 - 126
Date:	2016
Publisher:	ELSEVIER SCI LTD
Place of Publication:	OXFORD
ISSN:	2212-1684
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WIND; SALTATION; RESUSPENSION; EROSION; DEVILS Multiple languages Geography, Physical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26371