DSpace Collection:https://hdl.handle.net/10171/296792024-03-29T10:53:47Z2024-03-29T10:53:47ZDynamics of breaking arches under a constant vibrationhttps://hdl.handle.net/10171/543602023-03-28T09:46:36Z2017-01-01T00:00:00ZTitle: Dynamics of breaking arches under a constant vibration
Abstract: Granular flow through an orifice can be suddenly halted by the formation of arches in the vicinity of the outlet, which are stable under the action of gravity. They may be broken when an external driving (for instance, vibration) is applied. With the aim of shedding light on the dynamics of arch destruction, we built an experiment consisting of a vertical two-dimensional silo filled with monodisperse beads, to which a constant vibration is applied. It was previously found that an important parameter to predict the robustness of the arch is the angle between consecutive beads. We focus on long-enduring arches and study the angles among the beads along time. We have found that in many cases the dynamics of the largest angle determines the breaking of the arch; it does not only determine where the ¿weakest link¿ is, but also the process that leads to the final destabilization. This is interesting because it can provide information about whether the flow will resume in a well-defined time or not, which is especially useful for industrial processes that have to constantly deal with the possible emergence of clogs.2017-01-01T00:00:00ZCluster splitting in granular segregation driven by horizontal shakinghttps://hdl.handle.net/10171/543402023-03-28T09:46:36Z2017-01-01T00:00:00ZTitle: Cluster splitting in granular segregation driven by horizontal shaking
Abstract: In a recent work [C. Lozano et al. Phys. Rev. Lett 114, 178002 (2015)] segregation in an horizontally shaken granular layer was studied by analysing the particle-particle interactions in the simplest case possible of a two particles cluster. There, it was found that all clusters are transient (they eventually split if one waits long enough) and the probability distribution function of the separation times displays a power law tail, indicating that the splitting probability is not constant over time. Here, we extend this study to clusters of 3, 5, 10 and 20 particles where we also observe the power law decay of the distribution of cluster splitting time. In addition, we observe a weak increase of the average cluster splitting time with the cluster size, suggesting that interaction forces are non-additive. Finally, we show interesting statistics on the way in which clusters break suggesting that escaping of individual particles in the cluster borders is more likely than cluster breakage in subclusters of similar size.2017-01-01T00:00:00ZClogging and unclogging of many-particle systems passing through a bottleneckhttps://hdl.handle.net/10171/543232023-03-28T09:46:36Z2017-01-01T00:00:00ZTitle: Clogging and unclogging of many-particle systems passing through a bottleneck
Abstract: When a group of discrete particles pass through a narrowing, the flow may become arrested due to the
development of structures that span over the size of the aperture. Then, it is said that the system is clogged. Here,
we will discuss about the existence of a phase diagram for the clogged state that has been recently proposed,
arguing on its usefulness to describe different systems of discrete bodies ranging from granular materials, to
colloidal suspensions and live beings. This diagram is built based on the value of a flowing parameter which
characterizes the intermittent flow observed in all these discrete systems provided that there is an external or
internal energy supply. Such requirement, which is necessary to destabilize the clogging arches, is absent in a
standard static silo, which is therefore examined as a particular case. This view will help to understand some a
priori inconsistencies concerning the role of driving force in the clogging process that have been found in the
last years.2017-01-01T00:00:00ZTwisting, an alternative strategy to compact granular materialshttps://hdl.handle.net/10171/540762020-03-04T05:54:01Z2017-01-01T00:00:00ZTitle: Twisting, an alternative strategy to compact granular materials
Abstract: Nowadays, the common method to pack granular materials is to tap the ensemble against the gravity. Despite the apparent simplicity of that method, the asymptotic states reached by the tapped systems have strongly dependences on parameters like the shape of the tapping pulse, the container geometry or the ratio between lateral and axial dimensions. Beyond the restrictions imposed by the system boundaries, the particle shape (like rods or tetrahedrons) plays a central role in the evolution and the final state of the ensemble. In this work, we introduce an unconventional method for compacting granular ensembles by applying a sequence of alternating counterrotating pulses or ¿twists¿. By using spherical particles we analyze the efficiency of this method to achieve highly packed configurations.2017-01-01T00:00:00Z