  We present large-scale molecular dynamics simulations to study the free
evolution of granular gases. Initially, the density of particles is homogeneous
and the velocity follows a Maxwell-Boltzmann (MB) distribution. The system
cools down due to solid friction between the granular particles. The density
remains homogeneous, and the velocity distribution remains MB at early times,
while the kinetic energy of the system decays with time. However, fluctuations
in the density and velocity fields grow, and the system evolves via formation
of clusters in the density field and the local ordering of velocity field,
consistent with the onset of plug flow. This is accompanied by a transition of
the velocity distribution function from MB to non-MB behaviour. We used
equal-time correlation functions and structure factors of the density and
velocity fields to study the morphology of clustering. From the correlation
functions, we obtain the cluster size, $L$, as a function of time, $t$. We show
that it exhibits power law growth with $L(t)\sim t^{1/3}$
