MAESTRO, a low Mach number stellar hydrodynamics code, simulates long-time, low-speed flows that would be prohibitively expensive to model using traditional compressible codes. MAESTRO is based on an equation set derived using low Mach number asymptotics; this equation set does not explicitly track acoustic waves and thus allows a significant increase in the time step. MAESTRO is suitable for two- and three-dimensional local atmospheric flows as well as three-dimensional full-star flows, and adaptive mesh refinement (AMR) has been incorporated into the code. The expansion of the base state for full-star flows using a novel mapping technique between the one-dimensional base state and the Cartesian grid is also available.

NOTE: MAESTRO is no longer being actively developed. Users should switch to MAESTROeX (ascl:1908.019) to take advantage of the latest capabilities.

CASTRO is a multi-dimensional Eulerian AMR radiation-hydrodynamics code that includes stellar equations of state, nuclear reaction networks, and self-gravity. Initial target applications for CASTRO include Type Ia and Type II supernovae. CASTRO supports calculations in 1-d, 2-d and 3-d Cartesian coordinates, as well as 1-d spherical and 2-d cylindrical (r-z) coordinate systems. Time integration of the hydrodynamics equations is based on an unsplit version of the piecewise parabolic method (PPM) with new limiters that avoid reducing the accuracy of the scheme at smooth extrema. CASTRO can follow an arbitrary number of isotopes or elements. The atomic weights and amounts of these elements are used to calculate the mean molecular weight of the gas required by the equation of state. CASTRO supports several different approaches to solving for self-gravity. The most general is a full Poisson solve for the gravitational potential. CASTRO also supports a monopole approximation for gravity, and a constant gravity option is also available. The CASTRO software is written in C++ and Fortran, and is based on the BoxLib software framework developed by CCSE.

The software framework AMReX is designed for building massively parallel block-structured adaptive mesh refinement (AMR) applications. Key features of AMReX include C++ and Fortran interfaces; 1-, 2- and 3-D support; and support for cell-centered, face-centered, edge-centered, and nodal data. The framework also supports hyperbolic, parabolic, and elliptic solves on hierarchical adaptive grid structure, optional subcycling in time for time-dependent PDEs, and parallelization via flat MPI, OpenMP, hybrid MPI/OpenMP, or MPI/MPI, and parallel I/O. AMReX supports the plotfile format with AmrVis, VisIt (ascl:1103.007), ParaView (ascl:1103.014), and yt (ascl:1011.022).

MAESTROeX solves the equations of low Mach number hydrodynamics for stratified atmospheres or stars with a general equation of state. It includes reactions and thermal diffusion and can be used on anything from a single core to 100,000s of processor cores with MPI + OpenMP. MAESTROeX maintains the accuracy of its predecessor MAESTRO (ascl:1010.044) while taking advantage of a simplified temporal integration scheme and leveraging the AMReX software framework for block-structured adaptive mesh refinement (AMR) applications.