Our team has recently performed a series of experiments on silo discharge in low gravity environments. The paper is now published in Phys. Rev. E (see below). We prove that gravity plays an important role on the behavior of granular materials and more particularly on the packing fraction of a random assembly of spherical particles. This study provides relevant information for space exploration, since low gravity environments (such as asteroids) are poorly known.
More recently, we went to the Large Diameter Centrifuge (LDC) facility at ESA/ESTEC, the Netherlands. Accelerations up to 20g can be reached. See a video here. The idea was to extrapolate our low gravity results to hyper gravity in order to extract useful scaling laws. Data are still treated and analyzed. We will come back soon with the results.
S. Dorbolo et al, Phys. Rev. E 84, 041305 (2011) – PDF