GhostZone

Also referred to as a ghost region, this is an extended region around a grid that is used to calculate fluxes when integrating the grid. For root grids, these extended grid values are initialized during the problem setup. Higher-level grids have their ghost regions extrapolated from their parent grids. These ghost cells are not integrated along with the grid when the problem is advanced a step.

After every integration step, AstroBEAR calls SetGhost() to copy data from overlapping grids into a grid's ghost zones. This makes sure that data from a neighboring grid of similar resolution always takes precedence over extrapolated data when performing the next integration step.