  We report new dynamical modes in confined soft granular flows, such as
stochastic jetting and dripping, with no counterpart in continuum viscous
fluids. The new modes emerge as a result of the propagation of the chaotic
behaviour of individual grains -- here, monodisperse emulsion droplets to the
level of the entire system as the emulsion is focused into a narrow orifice by
an external viscous flow. We observe avalanching dynamics and the formation of
remarkably stable jets -- singlefile granular chains -- which occasionally
break, resulting in a non-Gaussian distribution of cluster sizes. We find that
the sequences of droplet rearrangements that lead to the formation of such
chains resemble unfolding of cancer cell clusters in narrow capillaries,
overall demonstrating that microfluidic emulsion systems could serve to model
various aspects of soft granular flows, including also tissue dynamics at the
meso-scale.
