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DY: Fachverband Dynamik und Statistische Physik
DY 10: Granular Physics 2 - organized by Matthias Sperl (Köln)
DY 10.6: Talk
Monday, March 22, 2021, 12:40–13:00, DYc
Flow in an hourglass: particle friction and stiffness matter — •Tamás Börzsönyi1, Tivadar Pongó1,2, Viktória Stiga1, János Török3, Sára Lévay3, Balázs Szabó1, Raúl Cruz Hidalgo2, and Ralf Stannarius4 — 1Wigner Research Centre for Physics, H-1525 Budapest, Hungary — 2Universidad de Navarra, Pamplona, Spain — 3Institute of Physics BME, Budapest, Hungary — 4Otto-von-Guericke-University, D-39106 Magdeburg, Germany
For usual granular materials the discharge rate from a silo is known to be time independent (constant flow rate). This is opposed to the case of a liquid for which the decreasing height leads to decreasing pressure, resulting in gradually decreasing flow rate during a discharge process. We performed laboratory experiments and numerical simulations with traditional (frictional hard) granular materials and grains with reduced surface friction and hardness. We show, that particle stiffness has a strong effect on the qualitative features of silo discharge. For deformable grains lowering the friction coefficient leads to a gradual change in the discharge curve: the flow rate becomes filling height dependent, it decreases during the discharge process. For hard grains the flow rate is much less sensitive to the value of the friction coefficient. For more details see Pongó et al., New J. Phys., (2021)