  Collisional self-interactions occurring in protostellar jets give rise to
strong shocks, the structure of which can be affected by radiative cooling
within the flow. To study such colliding flows, we use the AstroBEAR AMR code
to conduct hydrodynamic simulations in both one and three dimensions with a
power law cooling function. The characteristic length and time scales for
cooling are temperature dependent and thus may vary as shocked gas cools. When
the cooling length decreases sufficiently rapidly the system becomes unstable
to the radiative shock instability, which produces oscillations in the position
of the shock front; these oscillations can be seen in both the one and three
dimensional cases. Our simulations show no evidence of the density clumping
characteristic of a thermal instability, even when the cooling function meets
the expected criteria. In the three-dimensional case, the nonlinear thin shell
instability (NTSI) is found to dominate when the cooling length is sufficiently
small. When the flows are subjected to the radiative shock instability,
oscillations in the size of the cooling region allow NTSI to occur at larger
cooling lengths, though larger cooling lengths delay the onset of NTSI by
increasing the oscillation period.
