Evolution of Cold Shock-Bounded Slabs:

The Nonlinear Thin-Shell Instability

John M. Blondin and Brian S. Marks

Department of Physics, North Carolina State University, Raleigh NC 27695-8202

Abstract

The stability and evolution of cold, shock-bounded slabs is studied using numerical hydrodynamic simulations. We confirm the analysis of Vishniac, who showed that such slabs are unstable if they are perturbed by a displacement larger than their width. The growth rate of this nonlinear thin shell instability (NTSI) is found to increase with decreasing wavelength, in qualitative agreement with Vishniac's analysis. The NTSI saturates when the bending angle becomes large and the growth in the width of the slab pinches off the perturbation. After saturation, the slab remains greatly extended with an average density much less than the original slab density, supported primarily by supersonic turbulence within the slab. Linear perturbations are also found to be unstable in that they can lead to turbulent flow within the slab, although this response to linear perturbations is distinct from, and much less violent than the NTSI.

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ntsi.tar.Z compressed tar file of tex file and eps files.

ntsi.ps.Z compressed postscript file of paper submitted to New Astronomy.

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mAden.mpg Density of model A
mAmom.mpg Momentum of model A
mBden.mpg Density of model B
mGden.mpg Density of model G
cloud.mpg Density of Cloud impact

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