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J. Zhang, O. E. B. Messer, T. Plewa, A. M. Khokhlov (Univ. of Chicago)
Simulations of Type Ia supernova explosions are characterized by vastly disparate spatial scales, spanning some 12 orders of magnitude. This large dynamic range cannot be modeled in any single modern direct numerical simulation. Therefore, a subgrid model has to be employed in the supernova explosion simulations to describe physical processes taking place on unresolved scales.
We are concerned with the extension of the Khokhlov's subgrid flame model to a non-steady regime. We study the flame surface evolution subject to Rayleigh-Taylor instabilities in periodic domains. We seek correlations between the flame surface creation and destruction processes and basic parameters of the physical system. We found that in the fully developed turbulence the flame surface destruction strength is roughly constant and of the order of 1/L3, where L is the characteristic Rayleigh-Taylor bubble size.
The flame surface creation and destruction processes reflect the interplay between the Rayleigh-Taylor instability and the flame's tendency to smooth its surface. We found that this relationship can be well characterized by Froude number. In addition, the flame surface creation strength correlates with the magnitude of the vorticity component in the direction of gravitational acceleration. These findings provide a foundation for the future time-dependent subgrid flame model.
We thank J. B. Gallagher, S. Needham, D. Sheeler for their contributions to this project. This research has been supported by the U. S. Department of Energy contract B523820.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.