When a collimated stream, or jet, impacts a target, the
resulting spreading profile contains the signature of interactions among
the constituent particles, whether they are sub-atomic particles, molecules in
a liquid, or grains in a granular material. At the Chicago MRSEC, Jaeger,
Nagel, and Zhang investigated the impact of granular jets with noncircular
cross-sections, mimicking off-center collisions of subatomic particle beams.
Our results demonstrate how liquid-like behavior and collective hydrodynamic
flow emerge from strongly interacting discrete particles. These findings
resemble those from the Relativistic Heavy Ion Collider, where similar anisotropic
ejecta from a quark-gluon plasma have been observed in heavy-ion impact and
where the degree of anisotropy can similarly be controlled by the jet aspect
ratio.
