Release 23.08

23.08

• Time evolution without subcycling on the fine levels, which is enabled via
  the runtime parameter amr.subcycling_mode = "None", has been significantly
  rewritten to improve computational performance for certain cases. When the
  fine levels do not subcycle, the evolution can be done by processing all
  of the hydro updates on the fine level together and then immediately doing
  the flux correction to sync the coarse and fine level fluxes at the
  boundary between levels. This is how many AMR codes that do not subcycle
  are written. Castro now does this when the user chooses not to subcycle.
  The benefit of this approach is most evidence for problems with Poisson
  gravity that use a multigrid solve, as we can significantly reduce the
  number of Poisson solves per step, performing only a single composite
  (multi-level) solve at the new-time simultaneously for all levels. (#2505)