Localized instability of a granular layer
submitted to an ascending liquid flow

Collaboration with Patrick Rigord, Alessio Guarino and Valérie Vidal

Abstract

We study the response of an immersed granular material to an ascending liquid-flow; a pressure difference DP is imposed between the two horizontal free surfaces of a thin layer of glass beads, such that the liquid tends to flow upwards, and the resulting flow-rate v is measured. There exists a critical pressure difference DP* above which the granular material destabilizes, leading to the formation of a localized fountain of granular material at the upper free surface. Seen from above, the characteristic size of this localized instability is found to be proportional to the characteristic grain size, independent of both the flow-rate and the thickness of the granular layer. Destabilization of the granular layer is shown to take place when the pressure force counterbalances the weight of the granular layer.

Related publication

Localized instability of a granular layer submitted to an ascending liquid flow,
Rigord P., Guarino A., Vidal V. and Géminard J.-C., Granular Matter, 7 (2005) 191-197.