| Autor: |
Davidovits S; Lawrence Livermore National Laboratory, Livermore, California 94550, USA., Federrath C; Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia.; Australian Research Council Centre of Excellence in All Sky Astrophysics (ASTRO3D), Canberra, ACT 2611, Australia., Teyssier R; Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA., Raman KS; Lawrence Livermore National Laboratory, Livermore, California 94550, USA., Collins DC; Department of Physics, Florida State University, Tallahassee, Florida 32306, USA., Nagel SR; Lawrence Livermore National Laboratory, Livermore, California 94550, USA. |
| Abstrakt: |
An initially planar shock wave propagating into a medium of nonuniform density will be perturbed, leading to the generation of postshock velocity perturbations. Using numerical simulations we study this phenomenon in the case of highly nonuniform density (order-unity normalized variance, σ_{ρ}/ρ[over ¯]∼1) and strong shocks (shock Mach numbers M[over ¯]_{s}≳10). This leads to a highly disrupted shock and a turbulent postshock flow. We simulate this interaction for a range of shock drives and initial density configurations meant to mimic those which might be presently achieved in experiments. Theoretical considerations lead to scaling relations, which are found to reasonably predict the postshock turbulence properties. The turbulent velocity dispersion and turbulent Mach number are found to depend on the preshock density dispersion and shock speed in a manner consistent with the linear Richtymer-Meshkov instability prediction. We also show a dependence of the turbulence generation on the scale of density perturbations. The postshock pressure and density, which can be substantially reduced relative to the unperturbed case, are found to be reasonably predicted by a simplified analysis that treats the extended shock transition region as a single normal shock. |
