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DY: Fachverband Dynamik und Statistische Physik
DY 50: Granular Matter and Granular Dynamics II
DY 50.6: Vortrag
Donnerstag, 19. März 2020, 11:15–11:30, ZEU 160
Is the hourglass always flowing with a constant speed? — •Tamás Börzsönyi1, Tivadar Pongó1,2,3, Viktória Stiga1, János Török3, Sára Lévay3, Balázs Szabó1, 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 bin 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, grains with reduced surface friction and hardness, as well as non-spherical particles which develop orientational ordering during flow. We show, that grains with a small (<0.1) surface friction coefficient discharge with decreasing flow rate, while for frictional elongated grains the development of orientational ordering leads to increasing flow rate.