  Jamming describes a transition from a flowing or liquid state to a solid or
rigid state in a loose assembly of particles such as grains or bubbles. In
contrast, clogging describes the ceasing of the flow of particulate matter
through a bottleneck. It is not clear how to distinguish jamming from clogging,
nor is it known whether they are distinct phenomena or fundamentally the same.
We examine an assembly of disks moving through a random obstacle array and
identify a transition from clogging to jamming behavior as the disk density
increases. The clogging transition has characteristics of an absorbing phase
transition, with the disks evolving into a heterogeneous phase-separated
clogged state after a critical diverging transient time. In contrast, jamming
is a rapid process in which the disks form a homogeneous motionless packing,
with a rigidity length scale that diverges as the jamming density is
approached.
