Stability of freely falling granular streams
Abstract
A freely falling stream of weakly cohesive granular particles is modeled and analysed with help of event driven simulations and continuum hydrodynamics. The former show a breakup of the stream into droplets, whose size is measured as a function of cohesive energy. Extensional flow is an exact solution of the one-dimensional Navier-Stokes equation, corresponding to a strain rate, decaying like 1/t from its initial value, gammaDot0. Expanding around this basic state, we show that the flow is stable for short times (gammaDot0 * t << 1), whereas for long times (gammaDot0 * t >> 1) perturbations of all wavelength grow. The growthrate of a given wavelength depends on the instant of time when the fluctuation occurs, so that the observable patterns can vary considerably.
Cite
@article{arxiv.1203.1532,
title = {Stability of freely falling granular streams},
author = {Stephan Ulrich and Annette Zippelius},
journal= {arXiv preprint arXiv:1203.1532},
year = {2015}
}
Comments
4 page, 5 figures. Submitted to PRL. Supplementary material: see http://wwwuser.gwdg.de/~sulrich/research/#Publications