  Asymmetric obstacles can be exploited to direct the motion and induce sorting
of run-and-tumbling particles. In this work, we show that flocking particles
which follow the Vicsek model aligning rules experience a collective trapping
in the presence of a wall of funnels made of chevrons, concentrating at the
opposite side of a wall of funnels than run-and-tumbling particles. Flocking
particles can be completely trapped or exhibit a dynamical trapping behaviour;
these two regimes open the door to the design of a system with two
perpendicular flows of active particles. This systematic study broaden our
understanding about the emergence of collective motion of microorganisms in
confined environments and direct the design of new microfluidics devices able
to controlthese collective behaviours.
