Dresden 2020 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 50: Granular Matter and Granular Dynamics II
DY 50.2: Talk
Thursday, March 19, 2020, 10:15–10:30, ZEU 160
Is Janssen's effect still valid when simply filling a silo with non-moving bottom? — •Diego Sancho Martinez1, Ralf Stannarius1, Robin Shädel1, and Tamas Börzsönyi2 — 1Otto von Guericke Universität, Magdeburg, Germany — 2Wigner Institute for Solid State Physics, Budapest, Hungary
Grain storage has been a matter of special interest during the past centuries. In former times storage containers were small compared to current silos. The biggest problem that occurs in large silos is that the walls bear much of the weight contained in it. The saturation of the pressure at the base of the silo with height in a granular system was described in detail by Janssen and supported by posterior studies. Several recent studies show, that with mobilized contact forces (realized e.g. by slowly moving the silo wall upwards) the pressure saturates at small filling heights (comparable to the silo diameter D). Without mobilization the pressure depends on the history of the system. Here, we investigate the case of simple filling (without moving walls) for different materials: soft and nearly frictionless hydrogels, soft and highly friction round-shaped sponges as well as hard particles such as glass beads and airsoft beads. We find that the pressure at the bottom of the silo as a function of filling height does not saturate up to filling heights of 20D, but keeps increasing. The rate of increase appears to be constant above filling heights of about 3D.