Issue
EPL
Volume 83, Number 5, September 2008
Article Number 54004
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/83/54004
Published online 29 August 2008
EPL, 83 (2008) 54004
DOI: 10.1209/0295-5075/83/54004

Experimental evidence for a description of granular segregation in terms of the effective temperature

S. Sarkar and D. V. Khakhar

Department of Chemical Engineering, Indian Institute of Technology Bombay - Powai, Mumbai 400076, India

khakhar@iitb.ac.in

received 23 January 2008; accepted in final form 10 July 2008; published September 2008
published online 29 August 2008

Abstract
Granular segregation, spontaneous demixing of components in flowing mixtures, is a phenomenon of practical importance and occurs in a number of natural systems. We present a model to describe granular segregation due to density differences in a dense granular flow. Such flows are a prototype of "jammed" systems for which a new thermodynamics has been proposed arising from analysis of glassy systems and packed powders. In the context of this new framework, we show that granular segregation is determined by the effective temperature defined by the fluctuation-dissipation relation. The description has no fitted parameters and is validated by experiments. The work shows the utility of the effective temperature for the analysis of transport in granular flows and indicates the promise of the new thermodynamics for the description of practical systems.

PACS
45.70.Mg - Granular flow: mixing, segregation and stratification.
83.80.Fg - Granular solids.
61.43.Fs - Glasses.

© EPLA 2008