  Molecular clouds (MCs) are stellar nurseries, however, formation of stars
within MCs depends on the ambient physical conditions. MCs, over a free-fall
time are exposed to numerous dynamical phenomena, of which, the interaction
with a thin, dense shell of gas is but one. Below we present results from
self-gravitating, 3-D smoothed particle hydrodynamics ({\small SPH})
simulations of the problem; seven realisations of the problem have been
performed by varying the precollision density within the cloud, the nature of
the post-collision shock, and the spatial resolution in the computational
domain. Irrespective of the type of shock, a complex network of dense
filaments, seeded by numerical noise, readily appears in the shocked cloud.
Segregation of the dense and rarefied gas phases also manifests itself in a
bimodal distribution of gas density. We demonstrate that the power-spectrum for
rarefied gas is Kolomogorov like, while that for the denser gas is considerably
steeper. As a corollary to the main problem, we also look into the possibly
degenerative effect of the {\small SPH} artificial viscosity on the impact of
the incident shell. It is observed that stronger viscosity leads to greater
post-shock dissipation, that strongly decelerates the incident shock-front and
promotes formation of contiguous structure, albeit on a much longer timescale.
We conclude that too much viscosity is likely to enhance the proclivity towards
gravitational boundedness of structure, leading to unphysical fragmentation.On
the other hand, insufficient resolution appears to suppress fragmentation.
Convergence of results is tested at both extremes, first by repeating the test
case with more than a million particles and then with only half the number of
particles in the original test case.
