Clogging and jamming transitions in periodic obstacle arrays

Abstract

We numerically examine clogging transitions for bidisperse disks flowing through a two dimensional periodic obstacle array. We show that clogging is a probabilistic event that occurs through a transition from a homogeneous flowing state to a heterogeneous or phase separated jammed state where the disks form dense connected clusters. The probability for clogging to occur during a fixed time increases with increasing particle packing and obstacle number. For driving at different angles with respect to the symmetry direction of the obstacle array, we show that certain directions have a higher clogging susceptibility. It is also possible to have a size-specific clogging transition in which one disk size becomes completely immobile while the other disk size continues to flow.A loose collection of particles such as grains or bubbles can exhibit a transition from a flowing liquidlike state to a non-flowing or jammed state as a function of increasing density, where the density φ j at which the system jams is referred to as Point J 1-3 . One system in which jamming has been extensively studied is a bidisperse twodimensional (2D) packing of frictionless disks, where the area faction covered by the disks at Point J is approximately φ = 0.84, and where the system density is uniform at the jamming transition 1,2,4 . Related to jamming is the phenomenon of clogging, as observed in the flow of grains 5-8 or bubbles 9 through an aperture at the tip of a hopper. The clogging transition is a probabilistic process in which, for a fixed grain size, the probability of a clogging event occurring during a fixed time interval increases with decreasing aperture size. A general question is whether there are systems that can exhibit features of both jamming and clogging. For example, such combined effects could appear in a system containing quenched disorder such as pinning or obstacles where jammed or clogged configurations can be created by a combination of particles that are directly immobilized in a pinning site as well as other particles that are indirectly immobilized through contact with obstacles or pinned particles. In many systems where pinning effects arise, such as for superconducting vortices or charged particles, the particle-particle interactions are long range, meaning that there is no well defined areal coverage density 10 at which the system can be said to jam, so a more ideal system to study is an assembly of hard disks with strictly short range particle-particle interactions. Previous studies have considered the effect of a random pinning landscape on transport in a 2D sample of bidisperse hard disks 11 , while in other work on the effect of obstacles, the density at which jamming occurs decreases when the number of pinning sites or obstacles increases 12,13 .Here we examine a 2D system of bidisperse frictionless disks flowing through a square periodic obstacle array composed of immobile disks with an obstacle lattice constant of a. The total disk density, defined as the area coverage of the mobile disks and the obstacl...

Active particles with desired orientation flowing through a bottleneck

“…Such statistical features agree with a description of the intermittent flow in which the probability of blockage formation is constant over time, whereas the probability of getting the block destroyed depends on time. Interestingly, this behavior seems to hold for systems built of different constituents (such as colloids 2 – 4 , droplets 5 , granular 6 – 10 , vibration-driven vehicles 11 , animals 12 , 13 and pedestrians 14 ) as well as for different confining geometries (bottlenecks and obstacle arrays or porous materials 15 , 16 ).…”

Redefining the role of obstacles in pedestrian evacuation

“…In addition, the relationship between clogging and jamming is being a topic of discussion in the last years [14][15][16]. Basically, depending on the conditions, clogging may end up with the development of a completely jammed system [17] where the contact forces among particles increase notably in duration and intensity; for the pedestrian case, this process may often results in fatalities.…”

Clogging and jamming of colloidal monolayers driven across disordered landscapes

“…In contrast, the local and spatially heterogeneous nature of clogging makes this phenomenon more difficult to characterize and to control, despite its technological relevance.In previous experimental realizations, clogging has received much attention at the level of a single bottleneck [16], while studies addressing the dynamics of microscale systems driven through heterogeneous landscapes are rather scarce [5]. In contrast, recent theoretical works demonstrated the rich phenomenology of transport and clogging across ordered [17,18] or disordered [19,20] landscapes. The advantage of using colloidal particles as model systems for clogging is their flexibility, since external fields may be used to create driving forces for transport, or to tune in situ the pair interac-tions.Here we experimentally investigate the flow properties of a monolayer of paramagnetic colloidal particles that is driven across a heterogeneous landscape composed of disordered obstacles.…”