Astronomy and Astrophysics – Astronomy
Scientific paper
Aug 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995apj...449..727s&link_type=abstract
Astrophysical Journal v.449, p.727
Astronomy and Astrophysics
Astronomy
56
Hydrodynamics, Instabilities, Methods: Numerical, Shock Waves
Scientific paper
Radiative shocks perturbed from steady state are subject to an oscillatory overstability. We have examined the nature of this overstability in one and two dimensions using numerical hydrodynamic simulations. We find that one-dimensional simulations of a uniform flow incident upon a reflecting wall produce oscillation frequencies in agreement with those of earlier analytic (Chevalier & Imamura 1982) and numerical (Imamura, Wolff, & Durisen 1984) work. We do not, however, find any evidence for positive growth rates. This result is not in contradiction with previous linear analysis because the supersonic flow into a wall problem is at a saturated, nonlinear amplitude from the beginning. In the case of one-dimensional steady state shocks in the absence of a solid wall, we find a slightly different dependence of the overstability on α when we assume a cooling rate proportional to Tα. In this case oscillations in radiative shocks with α ≲ 0.75 are found to saturate at a finite amplitude, i.e., the relevant critical value of alpha is at least above 0.5. We also find high Mach number systems to be less stable than low Mach number systems subject to the same cooling law. Simulations of two-dimensional steady state shocks reveal that transverse perturbations in the shock front quickly manifest themselves in the cold, dense gas layer downstream of the cooling region. Perturbations in the cold gas layer are dominated by spatial wavelengths, λ ≲ Lc, the cooling length of the shock. The action of this instability ensures that interstellar radiative shocks will not be smooth on length scales of order the local cooling length.
Blondin John M.
Strickland Russell
No associations
LandOfFree
Numerical Analysis of the Dynamic Stability of Radiative Shocks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Numerical Analysis of the Dynamic Stability of Radiative Shocks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Numerical Analysis of the Dynamic Stability of Radiative Shocks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1269340