Docs: MR Ratio (#1589)

Document the experimental mesh-refinement ratio option.

1 files changed, 15 insertions, 1 deletions

diff --git a/Docs/source/running_cpp/parameters.rst b/Docs/source/running_cpp/parameters.rst
index d19b95831..13209cf5d 100644
--- a/Docs/source/running_cpp/parameters.rst
+++ b/Docs/source/running_cpp/parameters.rst
@@ -107,10 +107,24 @@ Setting up the field mesh
 * ``amr.n_cell`` (`2 integers in 2D`, `3 integers in 3D`)
     The number of grid points along each direction (on the **coarsest level**)
 
-* ``amr.max_level`` (`integer`)
+* ``amr.max_level`` (`integer`, default: ``0``)
     When using mesh refinement, the number of refinement levels that will be used.
 
     Use 0 in order to disable mesh refinement.
+    Note: currently, ``0`` and ``1`` are supported.
+
+* ``amr.ref_ratio`` (`integer` per refined level, default: ``2``)
+    When using mesh refinement, this is the refinement ratio per level.
+    With this option, all directions are fined by the same ratio.
+
+    Note: in development; currently, ``2`` is supported.
+
+* ``amr.ref_ratio_vect`` (3 `integer`s for x,y,z per refined level)
+    When using mesh refinement, this can be used to set the refinement ratio per direction and level, relative to the previous level.
+
+    Example: for three levels, a value of ``2 2 4 8 8 16`` refines the first level by 2-fold in x and y and 4-fold in z compared to the coarsest level (level 0/mother grid); compared to the first level, the second level is refined 8-fold in x and y and 16-fold in z.
+
+    Note: in development; currently allowed value: ``2 2 2``.
 
 * ``geometry.is_periodic`` (`2 integers in 2D`, `3 integers in 3D`)
     Whether the boundary conditions are periodic, in each direction.