Universität zu Köln

Born, Philip, Schmitz, Johannes and Sperl, Matthias (2017). Dense fluidized granular media in microgravity. NPJ Microgravity, 3. LONDON: SPRINGERNATURE. ISSN 2373-8065

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Abstract

Handling and transport of granular media are inevitably governed by the settling of particles. Settling into a dense state is one of the defining characteristics of granular media, among dissipation and absence of thermal agitation. Hence, settling complicates the adaptation of microscopic theories from atomic, molecular, or colloidal media to granular media. It is desirable to provide experiments in which selectively one of the granular characteristics is tuned to test suitable adaptation of a theory. Here we show that gas fluidization of granular media in microgravity is a suitable approach to achieve steady states closer to thermally agitated systems free of settling. We use diffusing-wave spectroscopy to compare the spatial homogeneity and the microscopic dynamics of gas-fluidized granular media on the ground and in drop tower flights with increasing packing densities up to full arrest. The gas fluidization on the ground leads to inhomogeneous states as known from fluidized beds, and partial arrest occurs at packing fractions lower than the full arrested packing. The granular medium in microgravity in contrast attains a homogeneous state with complete mobilization even close to full arrest. Fluidized granular media thus can be studied in microgravity with dynamics and packing fractions not achievable on the ground.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Born, Philip UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmitz, Johannes UNSPECIFIED UNSPECIFIED UNSPECIFIED Sperl, Matthias UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-211521
DOI:	10.1038/s41526-017-0030-z
Journal or Publication Title:	NPJ Microgravity
Volume:	3
Date:	2017
Publisher:	SPRINGERNATURE
Place of Publication:	LONDON
ISSN:	2373-8065
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PARTICLE; SCATTERING; POWDERS Multiple languages Multidisciplinary Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/21152