  The area of stochastic heat engines using active particles has attracted a
lot of attention recently. They have been shown to exhibit advantages over
engines using passive particles. In this work, we use multiple self-propelling
particles undergoing Vicsek-like aligning interaction as our working system.
The particles are confined in a two-dimensional circular trap. The interplay
between the confinement and the activity of the particles induces clustering.
These clusters change their locations relative to the walls of the trap, when
the wall steepness is varied with time. In this work we demonstrate that
changing the steepness of the wall and the activity of the particles
time-periodically can cause the system to act as an engine. In this setup, we
study the variations in extracted work with the activity, rotational diffusion,
and the Vicsek radius of individual particles. We also comment on the
complications involved in the definition of the engine efficiency in accordance
with the usual prescription of stochastic thermodynamics.
