Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA
Nature shuns homogeneity. In turbulent clouds, industrial reactors and geophysical flows, discrete particles arrange in clusters, posing difficult challenges to theory. A persistent question is whether clusters can be modelled with continuum equations. Recent evidence presented by Mitrano et al. (J. Fluid Mech., vol. 738, 2014, R2) indicates that suitable equations can predict the formation of clusters in granular flows, despite violating the simplifying assumptions upon which they are based.
(Received November 15 2013)
(Revised November 15 2013)
(Accepted December 09 2013)
(Online publication February 21 2014)
Email address for correspondence: [email protected]