.. _Chap:InputsMultigrid:
Multigrid solvers
=================
Nodal projection
----------------
The following inputs are defined using the ``nodal_proj`` prefix.
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| verbose | Verbosity of multigrid solver in nodal projection | Int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_verbose | Verbosity of BiCGStab solver in nodal projection | Int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_rtol | Relative tolerance in nodal projection | Real | 1.e-11 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_atol | Absolute tolerance in nodal projection | Real | 1.e-14 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| maxiter | Maximum number of iterations in the nodal projection | Int | 100 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_maxiter | Maximum number of iterations in the nodal projection | Int | 100 |
| | bottom solver if using bicg, cg, bicgcg or cgbicg | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_max_coarsening_level | Maximum number of coarser levels to allow in the nodal projection | Int | 100 |
| | If set to 0, the bottom solver will be called at the current level | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_solver | Which bottom solver to use in the nodal projection | String | bicgcg |
| | | | |
| | Options are bicgcg, bicgstab, cg, cgbicg, smoother or hypre | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_namespace | Namespace to use in the nodal projection when using hypre | String | hypre |
| | to control hypre specific settings. It can be any string. | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_interface | Which interface to use in the nodal projection when using hypre | String | ij |
| | | | |
| | Options are ij, semi_structured or structured | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
MAC projection
--------------
The following inputs are defined using the ``mac_proj`` prefix.
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+=========================+=======================================================================+=============+==============+
| verbose | Verbosity of multigrid solver in MAC projection | Int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_verbose | Verbosity of BiCGStab solver in MAC projection | Int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_rtol | Relative tolerance in MAC projection | Real | 1.e-11 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_atol | Absolute tolerance in MAC projection | Real | 1.e-14 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| maxiter | Maximum number of iterations in the MAC projection | Int | 200 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_maxiter | Maximum number of iterations in the MAC projection | Int | 200 |
| | bottom solver if using bicg, cg, bicgcg or cgbicg | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_max_coarsening_level | Maximum number of coarser levels to allow in the MAC projection | Int | 100 |
| | If set to 0, the bottom solver will be called at the current level | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_solver | Which bottom solver to use in the MAC projection | String | bicgcg |
| | | | |
| | Options are bicgcg, bicgstab, cg, cgbicg, smoother or hypre | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_namespace | Namespace to use in the MAC projection when using hypre | String | hypre |
| | to control hypre specific settings. It can be any string. | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_interface | Which interface to use in the MAC projection when using hypre | String | ij |
| | | | |
| | Options are ij, semi_structured or structured | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
Diffusion
---------
The following inputs are defined using the ``diffusion`` prefix.
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+=========================+=======================================================================+=============+==============+
| verbose | Verbosity of linear solver for diffusion solve | int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_verbose | Verbosity of BiCGStab solver in diffusion solve | int | 0 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_rtol | Relative tolerance in diffusion solve | Real | 1.e-11 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_atol | Absolute tolerance in diffusion solve | Real | 1.e-14 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| maxiter | Maximum number of iterations in diffusion solve | int | 100 |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_maxiter | Maximum number of iterations in diffusion solve | int | 100 |
| | bottom solver if using bicg, cg, bicgcg or cgbicg | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| mg_max_coarsening_level | Maximum number of coarser levels to allow in diffusion solve | int | 100 |
| | If set to 0, the bottom solver will be called at the current level | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bottom_solver | Which bottom solver to use in the diffusion solve | string | bicgcg |
| | | | |
| | Options are bicgcg, bicgstab, cg, cgbicg, or smoother | | |
+-------------------------+-----------------------------------------------------------------------+-------------+--------------+
Hypre Settings
--------------
`hypre` settings are specified using the following inputs which are read directly by AMReX when `hypre` is used as
the bottom solve for the MAC and/or nodal projections. By default, these inputs are defined using the
``hypre`` prefix, however different settings for the nodal and MAC projections can be used by specifying
a ``hpyre_namespace`` for each solver.
.. warning::
* MFIX-Exa must be built with `hypre` enabled to use `hypre` as the bottom solve.
* If `hypre` is used for the nodal and MAC projections, then either the ``hypre_namespace`` must be left as the default (``hypre``)
or unique name spaces must be provided for both.
These inputs follow the typical approach for using `hypre` in MFIX-Exa where `BoomerAMG` is employed as a preconditioner
and `GMRES` for the linear solver.
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_preconditioner | Type of preconditioner | string | none |
| | | | |
| | Options are BoomerAMG or euclid | | |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| recompute_preconditioner | Recompute preconditioner during runs | Bool | true |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| hypre_solver | Type of hypre solver | string | BoomerAMG |
| | | | |
| | Options are BoomerAMG, GMRES, COGMRES, LGMRES, FlexGMRES, BiCGSTAB, | | |
| | PCG or Hybrid | | |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| verbose | Verbosity of hypre | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| num_krylov | Number of iterations | int | 50 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
The following inputs are valid when using ``BoomerAMG`` as a preconditioner or solver.
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_verbose | Set BoomerAMG verbosity | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_logging | See HYPRE_BoomerAMGSetLogging | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_max_iterations | See HYPRE_BoomerAMGSetMaxIter | int | 1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_precond_tolerance | See HYPRE_BoomerAMGSetTol | Real | 0.0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_coarsen_type | See HYPRE_BoomerAMGSetCoarsenType | int | 6 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_cycle_type | See HYPRE_BoomerAMGSetCycleType | int | 1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_relax_order | See HYPRE_BoomerAMGSetRelaxOrder | int | 1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_relax_type | See HYPRE_BoomerAMGSetRelaxType | int | 6 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_down_relax_type | See HYPRE_BoomerAMGSetCycleRelaxType | int | 11 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_up_relax_type | See HYPRE_BoomerAMGSetCycleRelaxType | int | 11 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_coarse_relax_type | See HYPRE_BoomerAMGSetCycleRelaxType | int | 11 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_num_sweeps | See HYPRE_BoomerAMGSetNumSweeps | int | 2 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_num_down_sweeps | See HYPRE_BoomerAMGSetCycleNumSweeps | int | 2 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_num_up_sweeps | See HYPRE_BoomerAMGSetCycleNumSweeps | int | 2 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_num_coarse_sweeps | See HYPRE_BoomerAMGSetCycleNumSweeps | int | 1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_max_levels | See HYPRE_BoomerAMGSetMaxLevels | int | 20 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_strong_threshold | See HYPRE_BoomerAMGSetStrongThreshold | Real | 0.57 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_interp_type | See HYPRE_BoomerAMGSetInterpType | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_variant | See HYPRE_BoomerAMGSetVariant | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_keep_transpose | See HYPRE_BoomerAMGSetKeepTranspose | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_min_coarse_size | See HYPRE_BoomerAMGSetMinCoarseSize | int | 1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_max_coarse_size | See HYPRE_BoomerAMGSetMaxCoarseSize | int | 9 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_pmax_elmts | See HYPRE_BoomerAMGSetPMaxElmts | int | 4 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_agg_num_levels | See HYPRE_BoomerAMGSetAggNumLevels | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_agg_interp_type | See HYPRE_BoomerAMGSetAggInterpType | int | 4 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_agg_pmax_elmts | See HYPRE_BoomerAMGSetAggPMaxElmts | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_trunc_factor | See HYPRE_BoomerAMGSetTruncFactor | Real | 0.1 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| bamg_set_restriction | See HYPRE_BoomerAMGSetRestriction | int | 0 |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| | Description | Type | Default |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| adjust_singular_matrix | Should be true if the problem to be solved has singular matrix | Bool | false |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| overwrite_existing_matrix_files | Over-write existing matrix files | Bool | false |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
| write_matrix_files | Write out matrix into text files | Bool | false |
+-----------------------------------+-----------------------------------------------------------------------+-------------+--------------+
.. note::
This list is likely incomplete because the AMReX / `hypre` interface continues to evolve.