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33 T he Center for Astrophysical Thermonuclear Flashes at the University of Chicago—a collaboration between scientists primarily at Chicago and Argonne National Laboratory—studies the long-standing problem of thermonuclear flashes on the surfaces of compact stars (such as neutron stars and white dwarfs) and in the interior of white dwarfs (such as Type Ia(More)
We present simulations and performance results of nuclear burning fronts in supernovae on the largest domain and at the finest spatial resolution studied to date. These simulations were performed on the Intel ASCI-Red machine at Sandia National Laboratories using FLASH, a code developed at the Center for Astrophysical Thermonuclear Flashes at the University(More)
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)
The Beowulf parallel workstation combines 16 PC-compatible processing subsystems and disk drives using dual Ethernet networks to provide a single-user environment with 1 Gops peak performance, half a Gbyte of disk storage, and up to 8 times the disk I/O bandwidth of conventional workstations. The Be-owulf architecture establishes a new operating point in(More)
One method of discriminating between the many Type Ia progenitor scenarios is by searching for contaminating hydrogen and helium stripped from the companion star. However, this requires understanding the effect of the impact of the supernova shell on different companion stars to predict the amount of mass stripped and its distribution in velocity and solid(More)
The Convex SPP-1000 is the first commercial implementation of a new generation of scalable shared memory parallel computers with full cache coherence. It employs a hierarchical structure of processing communication and memory name-space management resources to provide a scalable NUMA environment. Ensembles of 8 HP PA-RISC 7100 microprocessors employ an(More)
We describe a new implicit-explicit hybrid method for solving the equations of hydrodynamics. The scheme is an extension of the explicit second-order piecewise-parabolic method (PPM) which is unconditionally stable. The scheme is thus of the Godunov type. It is conservative, accurate to second order in both space and time, and makes use of a nonlinear(More)
We present the results of a simulation of a wind-driven non-linear gravity wave breaking on the surface of a white dwarf. The " wind " consists of H/He from an accreted envelope, and the simulation demonstrates that this breaking wave mechanism can produce a well-mixed layer of H/He with C/O from the white dwarf above the surface. Material from this mixed(More)
Observed novae abundances and explosion energies estimated from observations indicate that there must be significant mixing of the heavier material of the white dwarf (C+O) into the lighter accreted material (H+He). Accordingly, nova models must incorporate a mechanism that will dredge up the heavier white dwarf material, and fluid motions from an early(More)