[FEM]implement Gmsh mesh property "MeshSizeFromCurvature"

src/Mod/Fem/femmesh/gmshtools.py

@@ -708,11 +708,17 @@ class GmshTools():
             geo.write("Mesh.CharacteristicLengthMin = " + str(0) + ";\n")
         else:
             geo.write("Mesh.CharacteristicLengthMin = " + str(self.clmin) + ";\n")
+        if hasattr(self.mesh_obj, "MeshSizeFromCurvature"):   
+            geo.write(
+                "Mesh.MeshSizeFromCurvature = " + str(self.mesh_obj.MeshSizeFromCurvature) +
+                "; // number of elements per 2*pi radians, 0 to deactivate\n"
+            )
         geo.write("\n")
         if hasattr(self.mesh_obj, "RecombineAll") and self.mesh_obj.RecombineAll is True:
             geo.write("// other mesh options\n")
             geo.write("Mesh.RecombineAll = 1;\n")
             geo.write("\n")
+            
         geo.write("// optimize the mesh\n")
         # Gmsh tetra optimizer
         if hasattr(self.mesh_obj, "OptimizeStd") and self.mesh_obj.OptimizeStd is True:
@@ -727,15 +733,16 @@ class GmshTools():
         # higher order mesh optimizing
         if hasattr(self.mesh_obj, "HighOrderOptimize") and self.mesh_obj.HighOrderOptimize is True:
             geo.write(
-                "Mesh.HighOrderOptimize = 1;  // for more HighOrderOptimize "
+                "Mesh.HighOrderOptimize = 1; // for more HighOrderOptimize "
                 "parameter check http://gmsh.info/doc/texinfo/gmsh.html\n"
             )
         else:
             geo.write(
-                "Mesh.HighOrderOptimize = 0;  // for more HighOrderOptimize "
+                "Mesh.HighOrderOptimize = 0; // for more HighOrderOptimize "
                 "parameter check http://gmsh.info/doc/texinfo/gmsh.html\n"
             )
         geo.write("\n")
+        
         geo.write("// mesh order\n")
         geo.write("Mesh.ElementOrder = " + self.order + ";\n")
         if self.order == "2":

src/Mod/Fem/femobjects/mesh_gmsh.py

@@ -212,6 +212,15 @@ class MeshGmsh(base_fempythonobject.BaseFemPythonObject):
             # https://forum.freecadweb.org/viewtopic.php?t=41738
             # https://forum.freecadweb.org/viewtopic.php?f=18&t=45260&start=20#p389494
 
+        if not hasattr(obj, "MeshSizeFromCurvature"):
+            obj.addProperty(
+                "App::PropertyIntegerConstraint",
+                "MeshSizeFromCurvature",
+                "FEM Gmsh Mesh Params",
+                "number of elements per 2*pi radians, 0 to deactivate"
+            )
+            obj.MeshSizeFromCurvature = (12, 0, 10000, 1)
+            
         if not hasattr(obj, "Algorithm2D"):
             obj.addProperty(
                 "App::PropertyEnumeration",

src/Mod/Fem/femtest/data/elmer/group_mesh.geo

@@ -14,11 +14,12 @@ Physical Volume("Solid1") = {1};
 // min, max Characteristic Length
 Mesh.CharacteristicLengthMax = 1e+22;
 Mesh.CharacteristicLengthMin = 8.0;
+Mesh.MeshSizeFromCurvature = 12; // number of elements per 2*pi radians, 0 to deactivate
 
 // optimize the mesh
 Mesh.Optimize = 1;
 Mesh.OptimizeNetgen = 0;
-Mesh.HighOrderOptimize = 0;  // for more HighOrderOptimize parameter check http://gmsh.info/doc/texinfo/gmsh.html
+Mesh.HighOrderOptimize = 0; // for more HighOrderOptimize parameter check http://gmsh.info/doc/texinfo/gmsh.html
 
 // mesh order
 Mesh.ElementOrder = 2;