Arching in the segregation process of a tapped column of bi-disperse disks

R. O. UÑAC; L.A. PUGNALONI; BENITO, J.G.; A. M. VIDALES

Carlos Paz

Workshop; XIII Latin American Workshop on Nonlinear Phenomena; 2013

We study numerically the evolution of the segregation patterns obtained when tapping a column of disks of a given size where the presence of one bigger disk (the intruder) or a set of them (mixture of big and small disks) is allowed. The size ratio between large and small disks can be varied. Simulations are performed using a pseudo-dynamic model that only takes into account the excluded volume restriction during the collision of disks. The disks are initially deposited in a rectangular die. For the case of one intruder, it is placed at the center of the base of the column. For the case of a set of intruders, they are randomly distributed inside the column. The tapping procedure is achieved by expanding the particles with an intensity A, and then, by allowing them to fall down due to gravity. The height and the velocity of the one-intruder case are measured as a function of the tapping number, size ratio and tapping intensity. For the case of a mixture of disks, tapped column is followed by measuring a set of segregation indices as a function of concentration and intensity A. The behavior of the arches of particles present during the setting up of segregation is followed. The incidence that arch distributions have on the segregation process is analysed. A comparison with the one-intruder case is performed. Arches seem to be the key for segregation when just geometrical features are present.