Add new stretching transformation to mesh tools

mesh_tools/example/planar_mesh_gen.nml

@@ -28,12 +28,11 @@
   mesh_file_prefix = 'planar_mesh'
   geometry       = 'spherical'
   topology       = 'non_periodic'
-  n_meshes       = 2
-  mesh_names     = 'mesh_A','mesh_B'
-  mesh_maps      = 'mesh_A:mesh_B'
+  n_meshes       = 1
+  mesh_names     = 'mesh_A'
   partition_mesh = .false.
   coord_sys      = 'll'
-  rotate_mesh    = .true.
+  rotate_mesh    = .false.
 /
 
 !==================================================================
@@ -51,16 +50,16 @@
 !       be a factor of the other.
 
 &planar_mesh
-  edge_cells_x    = 48, 24
-  edge_cells_y    = 24, 12
+  edge_cells_x    = 48,24
+  edge_cells_y    = 24,12
   domain_size     = 48.0, 24.0
   domain_centre   = 0.0, 0.0
   periodic_x      = .false.
   periodic_y      = .false.
   create_lbc_mesh = .true.
   lbc_rim_depth   = 1
   lbc_parent_mesh = 'mesh_A'
-  apply_stretch_transform = .false.
+  stretch_function = 'polynomial'
 /
 
 &partitions
@@ -79,10 +78,10 @@
 /
 
 &stretch_transform
-  cell_size_inner = 2.0, 2.0
-  cell_size_outer = 3.0, 3.0
-  n_cells_outer   = 2, 2
+  cell_size_inner = 0.0135,0.0135
+  cell_size_outer = 0.036,0.036
+  n_cells_outer   = 5, 5
   n_cells_stretch = 5, 5
-  stretching_on   = 'cell_centres'
+  poly_power      = 3
   transform_mesh  = 'mesh_A'
 /

mesh_tools/rose-meta/lfric-mesh_tools/HEAD/rose-meta.conf

@@ -319,16 +319,6 @@ ns=namelist/mesh/planar
 sort-key=Section-A03
 title=Planar
 
-[namelist:planar_mesh=apply_stretch_transform]
-compulsory=true
-description=Apply stretched grid transformation.
-help=Enables using a larger cell spacing in the outer region of the domain,
-    =compared to the inner region.
-!kind=default
-sort-key=Panel-D01
-trigger=namelist:stretch_transform: .true.;
-type=logical
-
 [namelist:planar_mesh=create_lbc_mesh]
 compulsory=true
 description=Create LBC mesh
@@ -470,6 +460,23 @@ help=Specifies whether the topology of the mesh should be periodic in the y dire
 sort-key=Panel-A10
 type=logical
 
+[namelist:planar_mesh=stretch_function]
+compulsory=true
+description=Type of stretch transformation applied to the unit mesh
+!enumeration=true
+help=The function applied is:
+    = Uniform: y = ax (uniform resolution)
+    = The following have a low resolution outer and a high resolution
+    = interior, with a stretch region in between.
+    = Inflation: y_n = y_n-1 + dy * inflation ** stretch
+    = Polynomial: y = bx + ax^n where n is the power
+!kind=default
+trigger=namelist:stretch_transform: this != "'uniform'";
+       =namelist:stretch_transform=stretching_on: this == "'inflation'";
+       =namelist:stretch_transform=poly_power: this == "'polynomial'";
+value-titles=uniform, inflation, polynomial
+values='uniform','inflation','polynomial'
+
 [namelist:rotation]
 compulsory=true
 ns=namelist/mesh/Rotation
@@ -605,6 +612,17 @@ range=0:
 sort-key=Panel-A04
 type=integer
 
+[namelist:stretch_transform=poly_power]
+compulsory=true
+description=Polynomial Power
+help=The polynomial stretch transform is
+    = y = bx + ax^n
+    = where n is the integer polynomial power.
+!kind=default
+range=2:
+sort-key=Panel-A04
+type=integer
+
 [namelist:stretch_transform=stretching_on]
 compulsory=true
 description=Locations to map stretching function

mesh_tools/rose-meta/lfric-mesh_tools/versions.py

@@ -31,3 +31,33 @@ def upgrade(self, config, meta_config=None):
         # Add settings
         return config, self.reports
 """
+
+class vn30_t270(MacroUpgrade):
+    # Upgrade macro for <TICKET> by <Author>
+
+    BEFORE_TAG = "vn3.0"
+    AFTER_TAG = "vn3.0_t270"
+
+    def upgrade(self, config, meta_config=None):
+        # Add settings
+        nml = "namelist:planar_mesh"
+        apply_stretch_transform = self.get_setting_value(
+            config, [nml, "apply_stretch_transform"])
+
+        if apply_stretch_transform == ".true.":
+            self.add_setting(
+                config,
+                [nml, "stretch_function"],
+                "'inflation'",
+            )
+        else:
+            self.add_setting(
+                config,
+                [nml, "stretch_function"],
+                "'uniform'",
+            )
+        self.remove_setting(
+            config, [nml, "apply_stretch_transform"]
+        )
+
+        return config, self.reports

mesh_tools/source/planar_mesh_generator.f90

@@ -172,11 +172,9 @@ program planar_mesh_generator
   logical :: periodic_y
   logical :: create_lbc_mesh
   integer(i_def) :: lbc_rim_depth
+  integer(i_def) :: stretch_function
 
   character(str_def) :: lbc_parent_mesh
-
-  logical :: apply_stretch_transform
-
   character(str_def) :: transform_mesh
 
   type(local_mesh_collection_type) :: local_mesh_collection
@@ -257,7 +255,7 @@ program planar_mesh_generator
     call nml_obj%get_value( 'create_lbc_mesh', create_lbc_mesh )
     call nml_obj%get_value( 'lbc_rim_depth', lbc_rim_depth )
     call nml_obj%get_value( 'lbc_parent_mesh', lbc_parent_mesh )
-    call nml_obj%get_value( 'apply_stretch_transform', apply_stretch_transform )
+    call nml_obj%get_value( 'stretch_function', stretch_function )
   end if
 
   if (configuration%namelist_exists('stretch_transform')) then
@@ -418,9 +416,9 @@ program planar_mesh_generator
     call log_event( log_scratch_space, LOG_LEVEL_ERROR )
   end if
 
-  if (apply_stretch_transform) then
-    ! This enables support meshes to be created with a variable
-    ! resolution stretching function.
+  ! This enables support meshes to be created with a variable
+  ! resolution stretching function.
+  if (configuration%namelist_exists('stretch_transform')) then
     do j=1, n_meshes
       if (trim(mesh_names(j)) == trim(transform_mesh)) then
         fine_mesh_edge_cells_x = edge_cells_x(j)
@@ -753,6 +751,7 @@ program planar_mesh_generator
                         periodic_y         = periodic_y,             &
                         domain_size        = domain_size,            &
                         domain_centre      = domain_centre,          &
+                        stretch_function   = stretch_function,       &
                         rotate_mesh        = rotate_mesh,            &
                         target_north_pole  = set_north_pole,         &
                         target_null_island = set_null_island )
@@ -789,6 +788,7 @@ program planar_mesh_generator
                         fine_mesh_edge_cells_y,                    &
                         periodic_x, periodic_y,                    &
                         domain_size, domain_centre,                &
+                        stretch_function    = stretch_function,    &
                         target_mesh_names   = target_mesh_names,   &
                         target_edge_cells_x = target_edge_cells_x, &
                         target_edge_cells_y = target_edge_cells_y, &