Issue
EPL
Volume 87, Number 1, July 2009
Article Number 14002
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/87/14002
Published online 24 July 2009
EPL, 87 (2009) 14002
DOI: 10.1209/0295-5075/87/14002

A response function perspective on yielding of wet granular matter

S. H. Ebrahimnazhad Rahbari, J. Vollmer, S. Herminghaus and M. Brinkmann

Max-Planck-Institute for Dynamics and Self-Organization, Department of Complex Fluids 37073 Göttingen, Germany, EU

juergen.vollmer@ds.mpg.de

received 6 April 2009; accepted in final form 22 June 2009; published July 2009
published online 24 July 2009

Abstract
When dry ganular matter is tilted beyond a critical angle $\theta _{c}$, grains start to flow until a state is reached where the slope of the surface is smaller than $\theta _{c}$. In dry granulates this relaxation preferentially involves surface fluxes. In contrast wet granulates yield in the bulk. We uncover the origin of this behaviour by focusing on the structure of the balance equations of the forces, rather than applying a continuum model. The predictive power of the approach is demonstrated by a parameter-free prediction of the yielding of 2D packings with thermal motion and mass disorder.

PACS
45.70.-n - Granular systems.
62.20.M- - Structural failure of materials.
68.08.Bc - Wetting.

© EPLA 2009