set default concave_resoltion=None, changelog entry

Author: dbochkov-flexcompute

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The method `Geometry.reflected` can be used to create a reflected copy of any geometry off a plane. As for other transformations, for efficiency, `reflected` `PolySlab` directly returns an updated `PolySlab` object rather than a `Transformed` object, except when the normal of the plane of reflection has a non-zero component along the slab axis, in which case `Transformed` is still returned.
 - Validation check for unit error in grid spacing.
 - Validation that when symmetry is imposed along a given axis, the boundary conditions on each side of the axis are identical.
+- Fields `convex_resolution`, `concave_resolution`, and `mixed_resolution` in `CornerFinderSpec` can be used to take into account the dimensions of autodetected convex, concave, or mixed geometric features when `dl_min` is automatically inferred during automatic grid generation.
 
 ### Changed
 - Supplying autograd-traced values to geometric fields (`center`, `size`) of simulations, monitors, and sources now logs a warning and falls back to the static value instead of erroring.

tidy3d/components/grid/corner_finder.py

@@ -45,7 +45,7 @@ class CornerFinderSpec(Tidy3dBaseModel):
     )
 
     concave_resolution: Optional[pd.PositiveInt] = pd.Field(
-        2,
+        None,
         title="Concave Region Resolution.",
         description="Specifies number of steps to use for determining `dl_min` based on concave featues."
         "If set to ``None``, then the corresponding `dl_min` reduction is not applied.",