  We study a type Ia supernova explosion using three-dimensional numerical
simulations based on reactive fluid dynamics. We consider a delayed-detonation
model that assumes a deflagration-to-detonation transition. In contrast to the
pure deflagration model, the delayed-detonation model releases enough energy to
account for a healthy explosion, and does not leave carbon, oxygen, and
intermediate-mass elements in central parts of a white dwarf. This removes the
key disagreement between simulations and observations, and makes a delayed
detonation the mostly likely mechanism for type Ia supernovae.
