  The mechanism through which meter-sized boulders grow to km-sized
planetesimals in protoplanetary discs is a subject of active research, since it
is critical for planet formation. To avoid spiralling into the protostar due to
aerodynamic drag, objects must rapidly grow from cm-sized pebbles, which are
tightly coupled to the gas, to large boulders of 1-100m in diameter. It is
already well known that over-densities in the gaseous component of the disc
provide potential sites for the collection of solids, and that significant
density structures in the gaseous component of the disc (e.g., spiral density
waves) can trap solids efficiently enough for the solid component of the disc
to undergo further gravitational collapse due to their own self-gravity. In
this work, we employ the PENCIL CODE to conduct local shearing sheet
simulations of massive self-gravitating protoplanetary discs, to study the
effect of anticyclonic transient vortices, or eddies, on the evolution of
solids in these discs. We find that these types of structures are extremely
efficient at concentrating small and intermediate-sized dust particles with
friction times comparable to, or less than, the local orbital period of the
disc. This can lead to significant over-densities in the solid component of the
disc, with density enhancements comparable to, and even higher, than those
within spiral density waves; increasing the rate of gravitational collapse of
solids into bound structures.
