  We investigate, by means of numerical simulations, the phenomenology of star
formation triggered by low-velocity collisions between low-mass molecular
clumps. The simulations are performed using an SPH code which satisfies the
Jeans condition by invoking On-the-Fly Particle Splitting. Clumps are modelled
as stable truncated (non-singular) isothermal, i.e. Bonnor-Ebert, spheres.
Collisions are characterised by M_0 (clump mass), b (offset parameter, i.e.
ratio of impact parameter to clump radius), and M (Mach Number, i.e. ratio of
collision velocity to effective post-shock sound speed). The gas subscribes to
a barotropic equation of state, which is intended to capture (i) the scaling of
pre-collision internal velocity dispersion with clump mass, (ii) post-shock
radiative cooling, and (iii) adiabatic heating in optically thick protostellar
fragments. The efficiency of star formation is found to vary between 10% and
30% in the different collisions studied and it appears to increase with
decreasing M_0, and/or decreasing b, and/or increasing M. For b<0.5 collisions
produce shock compressed layers which fragment into filaments. Protostellar
objects then condense out of the filaments and accrete from them. The resulting
accretion rates are high, 1 to 5 x 10^{-5} M_sun yr^{-1}, for the first 1 to 3
x 10^4 yrs. The densities in the filaments, n >~ 5 x 10^5 cm^{-3}, are
sufficient that they could be mapped in NH_3 or CS line radiation, in nearby
star formation regions.
