  I study the confinement-induced aggregation phenomenon in a minimal model of
self-propelled particles inside a channel. Starting from first principles, I
derive a set of equations that govern the density profile of such a system at
the steady-state, and calculate analytically how the aggregation at the walls
varies with the physical parameters of the system. I also investigate how the
gradient of the particle density varies if the inside of the channel is
partitioned into two regions within which the active particles exhibit distinct
levels of fluctuations in their directions of travel.
