  We present three-dimensional numerical simulations of turbulent combustion
converting a neutron star into a quark star. Hadronic matter, described by a
micro-physical finite-temperature equation of state, is converted into strange
quark matter. We assume this phase, represented by a bag-model equation of
state, to be absolutely stable. Following the example of thermonuclear burning
in white dwarfs leading to Type Ia supernovae, we treat the conversion process
as a potentially turbulent deflagration. Solving the non-relativistic Euler
equations using established numerical methods we conduct large eddy simulations
including an elaborate subgrid scale model, while the propagation of the
conversion front is modeled with a level-set method. Our results show that for
large parts of the parameter space the conversion becomes turbulent and
therefore significantly faster than in the laminar case. Despite assuming
absolutely stable strange quark matter, in our hydrodynamic approximation an
outer layer remains in the hadronic phase, because the conversion front stops
when it reaches conditions under which the combustion is no longer exothermic.
