  Szilard engine(SZE) is one of the best example of how information can be used
to extract work from a system. Initially, the working substance of SZE was
considered to be a single particle. Later on, researchers has extended the
studies of SZE to multi-particle systems and even to quantum regime. Here we
present a detailed study of classical SZE consisting of $N$ particles with
inter-particle interactions, i.e., the working substance is a low density
non-ideal gas and compare the work extraction with respect to SZE with
non-interacting multi particle system as working substance. We have considered
two cases of interactions namely: (i) hard core interactions and (ii) square
well interaction. Our study reveals that work extraction is less when more
particles are interacting through hard core interactions. More work is
extracted when the particles are interacting via square well interaction.
Another important result for the second case is that as we increase the
particle number the work extraction becomes independent of the initial position
of the partition, as opposed to the first case. Work extraction depends
crucially on the initial position of the partition. More work can be extracted
with larger number of particles when partition is inserted at positions near
the boundary walls.
