Limits to the universal flow rate of granular matter: Breakdown of Beverloo's scaling versus inelastic collapse.

M.A. MADRID; J.R. DARIAS; L.A. PUGNALONI

La Plata

Congreso; Pan­American Advanced Studies Institute (PASI) on Frontiers in Particulate Media: From Fundamentals to Applications; 2014

The Beverloo?s scaling for the flow rate of granular materials through orificeshas two distinctuniversality features. The most highlighted in the literature isrelated to the independence of flowrate with the height of the granular column.The little studied, yet most striking, is related to the factthat flow rate doesnot depend on the material properties of the grains (Young?s modulus,Poison?sratio, friction coefficient, effective restitution coefficient, etc). Weshow that this universality withrespect to the material properties can cease ifwork is done on the system at a high rate and thenumber of grains in thecontainer reduces. We then show compelling evidences that universality holds if and only if an effective inelastic collapse is at play during the flow of the granular sample.