We have studied the effect of small amounts of added liquid on the dynamic behavior of a granular system consisting of a mixture of glass beads of two different sizes. Segregation of the large beads to the top of the sample is found to depend in a nontrivial way on the liquid content. A transition to viscoplastic behavior occurs at a critical liquid content, which depends upon the bead size. We show that this transition can be interpreted as a condensation due to the hysteretic liquid bridge forces connecting the beads, and provide the corresponding phase diagram.
@article{arxiv.cond-mat/0302582,
title = {Mixing and condensation in a wet granular medium},
author = {Dimitrios Geromichalos and Mika M. Kohonen and Frieder Mugele and Stephan Herminghaus},
journal= {arXiv preprint arXiv:cond-mat/0302582},
year = {2009}
}