Reverse Janssen effect in narrow granular columns

Abstract

When grains are added to a cylinder, the weight at the bottom is smaller than the total weight of the column, which is partially supported by the lateral walls through wall/grain frictional forces. This is known as the Janssen effect. Via a combined experimental and numerical investigation, here we demonstrate a reverse Jansen effect whereby the fraction of the weight supported by the base overcomes one. We characterize the dependence of this phenomenon on the various control parameters involved, rationalize the physical process responsible for the emergence of the compressional frictional forces responsible for the anomaly, and introduce a model to reproduce our findings. Contrary to prior assumptions, our results demonstrate that the constitutive relation on a material element can depend on the applied stress.

Supplementary material included; Editor suggestion; Featured in Physics

References in corpus (5)

• Granular flow down an inclined plane: Bagnold scaling and rheology
• Experiments on Corn Pressure in Silo Cells -- Translation and Comment of Janssen's Paper from 1895
• Stresses in silos: Comparison between theoretical models and new experiments
• Pressure screening and fluctuations at the bottom of a granular column
• The Role of Solid Friction in the Sedimentation of Strongly Attractive Colloidal Gels

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