Knot Production And Jet Disruption Via Nonlinear Kelvin-Helmholtz Pinch Instabilities

In Physics of Energy Transport in Extragalactic Radio Sources, 150-168, 1985, ed. A. Bridle and J. Eilek (NRAO: Green Bank), with M. Norman and K.-H. Winkler. (1985).

Abstract

We summarize the results of time-dependent numerical hydrodynamical simulations which investigate the behavior of pinching modes of the Kelvin-Helmholtz instability In the nonlinear regime. Ordinary mode (OM) pinch instabilities. important only at Mach numbers of order unity. are shown to be disruptive. Reflection mode CAM> pinch instabilities. Important in supersonic Jets with parameters of astrophysical interest. are shown to be not disruptive. but rather saturate at finite amplitude through the formation of oblique · Internal shockwaves. The saturated RM pinch Instability consists of a near-periodic train of biconical Internal shockwaves which propagates with a fraction of the mean flow velocity. Properties of the shock system are given for jets of different density ratios and Mach numbers. The effect of pinch Instabilities on energy transport in extragalactic Jets ts discussed.