Materials that climb up vibrating tubes
Scientists have discovered a phenomenon whereby granular material climbs up a vertically vibrating tube that is partially inserted in a granular silo. The final height to which the material climbs is found to depend on the strength of the vibrations and the depth to which the tube is inserted.
This effect is not seen in liquids or solids, but because granular materials show both solid- and liquid-like properties the periodic variation in the force between the tube and the particles causes them to climb. The effect is still seen when all the air in the system is removed.
By analyzing the forces acting on the particles the authors present a model that explains the phenomenon and that is consistent with experimental results.
Original publication
Chuanping Liu, Ping Wub and Li Wang, Soft Matter, 2013
