A. Nonaka, A. J. Aspden, M. Zingale, A. S. Almgren, J. B. Bell, S. E. Woosley
We extend our previous three-dimensional, full-star simulations of the final
hours of convection preceding ignition in Type Ia supernovae to higher
resolution using the adaptive mesh refinement capability of our low Mach number
code, MAESTRO. We report the statistics of the ignition of the first flame at
an effective 4.34 km resolution, and general flow field properties at an
effective 2.17 km resolution. We find that off-center ignition is likely, with
radius of 50 km most favored and a likely range of 40 to 75 km. This is
consistent with our previous coarser (8.68 km resolution) simulations, implying
that we have achieved sufficient resolution in our determination of likely
ignition radii. The dynamics of the last few hot spots preceding ignition
suggest that a multiple ignition scenario is not likely. With improved
resolution, we can more clearly see the general flow pattern in the convective
region, characterized by a strong outward plume with a lower speed
recirculation. We show that the convective core is turbulent with a Kolmogorov
spectrum and has a lower turbulent intensity and larger integral length scale
than previously thought (on the order of 16 km s$^{-1}$ and 200 km,
respectively), and we discuss the potential consequences for the first flames.
View original:
http://arxiv.org/abs/1111.3086
No comments:
Post a Comment