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Some Challenges in Calculating the Rayleigh-Taylor
Instability
Praveen Ramaprabhu
Center for Nonlinear Studies, LANL
Hosted by Paul Fischer
11:00 AM, June 16, 2006
Building 221, Room A216
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| Abstract |
Rayleigh-Taylor (RT) instability results when a light fluid accelerates
a
heavier fluid. This canonical flow is observed in the ejecta of
supernovae, and in the inertial confinement fusion process, where it can
temper the thermonuclear yield. The turbulent stage of the RT flow is
characterized by, among other parameters, the growth rate of the
mix-width envelope. However, numerical simulations from several
benchmark codes consistently produce lower RT growth rates (by 100%) than
experimentally measured values. Using carefully designed numerical
simulations, we find that the discrepancy is due to differences in the
initial conditions -- a broadband initial spectrum can produce the higher
growth rates observed in experiments, while an annular spectrum leads to
a lower-bound, universal value of alpha.
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