Numerical simulations of protostellar jets with nonequilibrium cooling. II: Models of pulsed jets

In this second of three papers, we present multidimensional time-dependent numerical simulations of the propagation of protostellar jets into a uniform ambient medium which utilize a nonequilibrium treatment of optically thin radiative cooling. This paper focuses on two- and three-dimensional models of pulsed jets in which the jet inlet velocity is assumed to be intrinsically variable. These models are motivated by recent observations which suggest temporal variability may account for knots of emission detected in the jet beam in several sources. Our simulations show that large-amplitude periodic variations as required by observations produce pulses which quickly steepen into shocks