NONLINEAR DYNAMICS OF A 3-DIMENSIONAL JET

被引:40
作者
HARDEE, PE [1 ]
CLARKE, DA [1 ]
机构
[1] UNIV ILLINOIS,BECKMAN INST,NATL CTR SUPERCOMP APPLICAT,URBANA,IL 61801
关键词
GALAXIES; JETS; HYDRODYNAMICS; INSTABILITIES;
D O I
10.1086/186636
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A three-dimensional hydrodynamical simulation of a cylindrical jet initialized across a Cartesian grid has been performed. The jet is driven at the origin by a small-amplitude precession to break the symmetry and excite helical modes of the Kelvin-Helmholtz instability. The simulation reveals a wealth of structures including filaments twisted around the circumference of the jet. Rapid spatial growth of relatively small amplitude filaments that can be attributed to high-order Kelvin-Helmholtz fluting modes is overwhelmed at larger distance by a slower spatially growing helically twisted elliptical distortion of the jet cross section. At slightly larger spatial scales, the jet is helically twisted and the flow bifurcates (trifurcates) as a further development of the elliptical (triangular) Kelvin-Helmholtz fluting modes. The observed behavior of this simulation is in good agreement with linear stability theory. The observed large-amplitude bifurcation of the flow into a helically twisted filament pair overlaying a helical twist of the whole jet appears similar to the observed oscillation and twisted filament pair seen in the Cygnus A jet. The small-amplitude multiple filamentation observed appears similar to the filamentation seen in the M87 jet inside knot A.
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页码:L9 / &
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