  Current practice in stellar evolution is to employ one-dimensional
calculations that quantitatively apply only to a minority of the observed stars
(single non-rotating stars, or well detached binaries). Even in these systems,
astrophysicists are dependent on approximations to handle complex
three-dimensional processes like convection. Understanding the structure of
binary stars, like those that lead to the Type Ia supernovae used to measure
the expansion of the universe, are grossly non-spherical and await a 3D
treatment.
  To approach very large problems like multi-dimensional modeling of stars, the
Lawrence Livermore National Laboratory has invested in massively parallel
computers and invested even more in developing the algorithms to utilize them
on complex physics problems. We have leveraged skills from across the lab to
develop a 3D stellar evolution code, Djehuty (after the Egyptian god for
writing and calculation) that operates efficiently on platforms with thousands
of nodes, with the best available physical data (opacities, EOS, etc.). Djehuty
has incorporated all basic physics for modeling stars including an accurate
equation of state, radiation transport by diffusion, thermonuclear reaction
rates, and hydrodynamics, and we have begun testing it in a number of
applications.
