Tp. Downes et Tp. Ray, NUMERICAL SIMULATIONS OF THE KELVIN-HELMHOLTZ INSTABILITY IN RADIATIVELY COOLED JETS, Astronomy and astrophysics, 331(3), 1998, pp. 1130-1142
We present the results of simulations of the development of the Kelvin
-Helmholtz (KH) instability in a cooled, slab symmetric system. The pa
rameters were chosen to approximate the physical conditions typically
found in jets from young stellar objects (YSOs). The effect of differe
nt methods of maintaining the initial equilibrium were examined for va
rying density. In addition, the effect of adjusting the width of the s
hear layer between the jet and ambient material was studied and found
not to have significant long-term effects on the development of the in
stability. We find that, in general, cooling acts to increase the leve
l of mixing between jet and ambient material through the 'breaking' of
KH induced waves on the surface of the jet increase the amount of mom
entum transferred from jet material to ambient material increase the t
ime taken for shocks to develop in the flow reduce the strength of the
se shocks reduce the rate of decollimation of momentum flux The first
and second of these results appear to contradict the conclusions of Ro
ssi et al. (1997) who carried out a similar study to ours but in cylin
drical symmetry. It is found, however, that the differences between sl
ab and cylindrical symmetry, while insignificant in the linear regime,
explain the apparent discrepancy between our results and those of Ros
si et al. (1997) in the non-linear regime.