Merge branch 'BoxmeshStagSizeVar' into 'master'

Added option in boxmesh to use a variable block shift size in staggered periodic bc

See merge request !70

PGLW/main/boxmesh.py

@@ -55,8 +55,10 @@ class BoxMesh(Domain):
             Block size, by default 32
         filename : str, optional
             Name of grid, by default 'grid.x3dunf'
-        staggered : bool, optional
-            For cyclic BC remapping, by default False
+        staggered : bool or int, optional
+            If True, cyclic BC remapping is used with 1 block shift.
+            Default False means no shift. If set to non-zero integer
+            then a shift size of this number of blocks is applied.
         printscreen:
             Print final grid parameters to screen similar to boxf90
         """
@@ -189,7 +191,7 @@ class BoxMesh(Domain):
                     self.add_blocks(b_i)
 
         # Add shift (assume z-direction is ground and top)
-        if self.staggered:
+        if int(self.staggered) != 0:
             if nbj > 96:
                 print(
                     "ERROR: the number of blocks in y-dir is",
@@ -200,9 +202,7 @@ class BoxMesh(Domain):
             for k in range(nbk):
                 for j in range(nbj):
                     in_ind = nbj + 1 - j - 1
-                    out_ind = nbj - j - 1
-                    if out_ind == 0:
-                        out_ind = nbj
+                    out_ind = ((nbj - j - int(self.staggered) - 1) % nbj) + 1
                     in_ind = 501 + in_ind
                     out_ind = 501 + out_ind
                     in_name = str(k) + "_" + str(j) + "_0"