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We present a case study of validating an astrophysical simulation code. Our study focuses on validating FLASH, a parallel, adaptive-mesh hydrodynamics code for studying the compressible, reactive flows found in many astrophysical environments. We describe the astrophysics problems of interest and the challenges associated with simulating these problems. We(More)
Results of the Ðrst spherically diverging, hydrodynamically unstable laboratory experiments of relevance to supernovae (SNe) are reported. The experiments are accomplished by using laser radiation to explode a hemispherical capsule, having a perturbed outer surface, which is embedded within a volume of low-density foam. The evolution of the experiment, like(More)
Laser-driven experiments are described which probe the interaction of a very strong shock with a spherical density inhomogeneity. The interaction is viewed from two orthogonal directions enabling visualization of both the initial distortion of the sphere into a double vortex ring structure as well as the onset of an azimuthal instability that ultimately(More)
Perturbation imprinting at a flat interface by a rippled shock has been observed in a laser hydrodynamics experiment. A strong shock was driven through a three-layer target, with the first interface rippled, and the second flat. The chosen thickness of the second layer gave instability growth with opposite phases at the two interfaces, consistent with(More)
The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant(More)
We investigate hydrodynamic instability of accelerating ionization fronts using two dimensional hydrodynamic simulations that include detailed energy de-position and release due to the absorption of UV radiation, recombination of hydrogen, radiative molecular cooling, and magnetic pressure. We consider linear perturbation growth and find that the(More)
We investigate on the National Ignition Facility the ablative Rayleigh-Taylor instability in the transition from weakly nonlinear to highly nonlinear regimes. A planar plastic package with preimposed two-dimensional broadband modulations is accelerated for up to 12 ns by the x-ray drive of a gas-filled Au radiation cavity with a radiative temperature(More)
We investigate numerically the hydrodynamic instability of an ionization front (IF) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes. When the initial amplitude is small, the imposed perturbation is completely stabilized and does not grow. When the initial perturbation amplitude is large enough, roughly the(More)
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