Flow and jamming of granular mixtures through obstaclesF. Chevoir1, F. Gaulard1 and N. Roussel2
1 LMSGC, Institut Navier - 2 allée Kepler, 77 420 Champs sur Marne, France
2 Laboratoire Central des Ponts et Chaussées - 58 Boulevard Lefebvre, 75015 Paris, France
received 25 October 2006; accepted in final form 15 May 2007; published July 2007
published online 6 June 2007
Due to the formation of arches, granular materials may jam when flowing through obstacles, as in the case of hoppers. As a way to quantify this process, we study experimentally the flow of binary granular mixtures through sieves, as a function of two parameters: the proportion of large grains and the ratio of large grains to sieve hole size. We distinguish three regimes: steady flows, jamming, and progressive clogging. In the case of steady flows, we measure the dependencies of the flow rate on the two parameters and observe a generalization of the law known for mono-disperse grains flowing through a single aperture. Moreover we measure how the critical size of the holes leading to jamming depends on the proportion of large grains. In the case of progressive clogging, we measure the slowing down of the flow rate and identify two mechanisms associated to the trapping of the large grains in the holes of the sieves and then to the formation of a filtration cake.
45.70.Mg - Granular flow: mixing, segregation and stratification.
81.05.Rm - Porous materials; granular materials.
© Europhysics Letters Association 2007