Josef Stein

Abstract for-loops over several aggregates

FOR-LOOPS OVER SEVERAL AGGREGATES Felix J. FRIDMAN Computer Science Department, 77ze Hebrew University, Jerusalem, Israel Glenn H. HOLLOWAY Aiken Computation Laboratory, Harvard University, Cambridge, MA 02138, U.S.A.

Line shifts in plasmas: A quantum mechanical approach

Abstract The problem of line-shifts in LTE plasmas is addressed in this study, in the framework of static ions and “active spectator” model. Although the work is still in progress, we can show that line-shifts, as predicted by Skupsky, are correct at high plasma temperatures, while at low temperatures the shift may differ from Skupskys value. Lines can have unshifted (or slightly shifted) peaks with asymmetric tails if the free electron wavefunctions are strongly localized by the random field of the plasma or by dynamic effects.

3D Simulations of Rayleigh-Taylor Instability Using “Vulcan/3D”

The growth rate of the turbulent mixing zone, which develops from random perturbations under Rayleigh-Taylor instability, has been studied using the 3D version of the hydrodynamical code VULCAN. Previous studies show large differences between the a parameter of different codes. In its Eulerian mode VULCAN/3D employs Van-Leer scheme for the advection of all variables, and can also use interface tracking for multi-phase flows. Simulations using parallel version of VULCAN/3D give α of about 0.06, a value which agrees very well with experiments and some other simulations.

Dependence analysis for outer loop parallelization of existing Fortran‐77 programs

We have used six static parallelization tools on four Fortran-77 programs used in physics simulations. We indicate areas where current tools have difficulties in recognizing parallelism, and illustrate these issues with simple examples. We suggest that a dynamic dependency analysis tool is needed to aid the user in the parallelization of dusty decks.