  Powerful stellar winds and supernova explosions with intense energy release
in the form of strong shock waves can convert a sizeable part of the kinetic
energy release into energetic particles. The starforming regions are argued as
a favorable site of energetic particle acceleration and could be efficient
sources of nonthermal emission. We present here a non-linear time-dependent
model of particle acceleration in the vicinity of two closely approaching fast
magnetohydrodynamic (MHD) shocks. Such MHD flows are expected to occur in rich
young stellar cluster where a supernova is exploding in the vicinity of a
strong stellar wind of a nearby massive star. We find that the spectrum of the
high energy particles accelerated at the stage of two closely approaching
shocks can be harder than that formed at a forward shock of an isolated
supernova remnant. The presented method can be applied to model particle
acceleration in a variety of systems with colliding MHD flows.
