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Etude théorique et expérimentale de la densification des milieux granulaires

Abstract : This thesis deals with the slow densification of a packing of grains under repeated taps. The granular compaction is treated by complementary numerical and experimental approaches. This problematic bears also a conceptual analogy with supercooled liquids and glasses. First, we present a numerical model simulating the compaction which reproduces almost all the experimental phenomenology. The principal asset of the model is to allow a local analysis of the packings. By means of various experimental set-ups, the effect of tapping on a bead packing has been carried out in detail. The one-tap dynamical response is first analysed. On the large scale, it reveals a nearly instantaneous relaxation whereas, on the small scale, slight individual events are still observed a long time after the tap. For a succession of taps, the different static configurations of the packing are shown to slowly relax towards a final steady-state. This evolution is very well fitted by the standard law used in the context of glassy relaxations. The kinetics of compaction seems to be ruled by an Arrhenius-like relation where the acceleration of the taps plays a role almost equivalent to a temperature. In parallel to compaction, a whole convective process is observed. Despite a slight intensity, it can have serious consequences at the long time. Generally speaking, an increase of the friction at the walls, or a decrease of the lateral spacing, result in a slowing down of compaction as well as convection. Otherwise, both phenomena obviously occur even if there is no more a collective take-off of the packing. It means that, after a sufficient time, small individual motions can lead the whole system to a marked restructuration.
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https://tel.archives-ouvertes.fr/tel-00001818
Contributor : Pierre Philippe <>
Submitted on : Monday, October 14, 2002 - 5:05:32 PM
Last modification on : Tuesday, January 12, 2021 - 4:40:12 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 6:05:34 PM

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  • HAL Id : tel-00001818, version 1

Citation

Pierre Philippe. Etude théorique et expérimentale de la densification des milieux granulaires. Dynamique des Fluides [physics.flu-dyn]. Université Rennes 1, 2002. Français. ⟨tel-00001818⟩

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