diff --git a/Docs/sphinx_documentation/source/LinearSolvers.rst b/Docs/sphinx_documentation/source/LinearSolvers.rst index c2ffe25fef2..958444bb2f0 100644 --- a/Docs/sphinx_documentation/source/LinearSolvers.rst +++ b/Docs/sphinx_documentation/source/LinearSolvers.rst @@ -380,17 +380,21 @@ Available choices are - :cpp:`MLMG::BottomSolver::petsc`: Currently for cell-centered only. - :cpp:`LPInfo::setAgglomeration(bool)` (by default true) can be used - continue to coarsen the multigrid by copying what would have been the - bottom solver to a new :cpp:`MultiFab` with a new :cpp:`BoxArray` with - fewer, larger grids, to allow for additional coarsening. + to copy the current level of multigrid data to fewer, larger + boxes. Two advantages of using this option is that the bottom solver will become + smaller, and communication overhead is reduced. + +- :cpp:`LPInfo::setAgglomerationGridSize(int)` (by default 8 in 1D, 16 in 2D, 32 in 3D) + if agglomeration is used, when the average box size becomes smaller than agg_grid_size^{DIM}, + boxes will agglomerate until this is no longer the case. Note that this action is + recursive and can happen at several different levels in the multigrid hierarchy. - :cpp:`LPInfo::setConsolidation(bool)` (by default true) can be used continue to transfer a multigrid problem to fewer MPI ranks. There are more setting such as :cpp:`LPInfo::setConsolidationGridSize(int)`, :cpp:`LPInfo::setConsolidationRatio(int)`, and :cpp:`LPInfo::setConsolidationStrategy(int)`, to give control over how this - process works. - + process works. If agglomeration is used, consolidation is ignored. :cpp:`MLMG::setThrowException(bool)` controls whether multigrid failure results in aborting (default) or throwing an exception, whereby control will return to the calling