Statistics – Computation
Scientific paper
Aug 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002aps..ccp.h2001k&link_type=abstract
American Physical Society, Division of Computational Physics Annual Meeting: , abstract #H2.001
Statistics
Computation
Scientific paper
We consider a Type Ia supernova explosion originating as a deflagration in the center of a carbon-oxygen Chandrasekhar-mass white dwarf (WD). A three-dimensional (3D) numerical model is based on reactive Euler equations of fluid dynamics coupled with an equation of state for a degenerate matter and a reduced nuclear reaction network. The energy-release model provides the correct propagation velocity for a laminar flame and takes into account carbon burning, as well as nuclear statistical quasi-equilibrium and equilibrium relaxations. The model for the turbulent burning on scales that are not resolved in the simulations is based on the assumption that burning on small scales is driven by the gravity-induced Rayleigh-Taylor (RT) instability. We performed 3D calculations and analysis for the first 1.9 seconds of explosion using an adaptively refined, fully threaded tree structured mesh covering a computational domain of size 6E+9 cm. For the highest-resolution case, the minimum cell size was 2.6 E+5 cm, and the mesh consisted of 100,000,000 computational cells by the end of the simulation. The flame, started as a sphere with the radius 3E+6 cm, becomes very convoluted due to the RT and Kelvin-Helmholtz instabilities on resolved scales and develops multiple buoyant plumes. As the plumes grow, the unburnt material either sinks towards the center or expands more slowly than the burnt material inside the plumes. The material burns at all distances from the center even when the larger flame plumes reach the outer layers of the star. By 1.9 seconds, some of these plumes approach the surface of the expanding WD that extends to (5-6) E+8 cm from the center. About 50% of the material burns out releasing 1.3E+51 ergs of nuclear energy which results in the explosion energy of about 7E+50 ergs at infinity. The expansion velocity at the surface reaches $1.2E+9 cm/s and continues to grow. An extensive convergence study shows that at high resolutions, the results become practically independent on the computational cell size and insensitive to subgrid model parameters.
Chtchelkanova Almadena
Gamezo Vadim
Khokhlov Alexei
Lanzagorta Marco
Oran Elaine
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