Fix for boundary marker error

src/underworld3/discretisation.py

@@ -1,4 +1,6 @@
 from typing import Optional, Tuple, Union
+from enum import Enum
+
 import os
 import numpy
 import sympy
@@ -189,10 +191,19 @@ def __init__(
                     % (plex_or_meshfile, ext[1:])
                 )
 
+        if boundaries is None:
+            class replacement_boundaries(Enum):
+                Null_Boundary = 666
+                All_Boundaries = 1001
+
+            boundaries = replacement_boundaries
+
         self.filename = filename
         self.boundaries = boundaries
         self.boundary_normals = boundary_normals
 
+
+
         # options.delValue("dm_plex_gmsh_mark_vertices")
         # options.delValue("dm_plex_gmsh_multiple_tags")
         # options.delValue("dm_plex_gmsh_use_regions")
@@ -229,8 +240,8 @@ def __init__(
                     # Load this up on the stacked BC label
                     if label_is:
                         stacked_bc_label.setStratumIS(b.value, label_is)
-                        
-            
+
+
 
             uw.mpi.barrier()
 

src/underworld3/systems/solvers.py

@@ -213,8 +213,8 @@ def __init__(
 
         self._v = self._v_projector.Unknowns.u
 
-        # If we add smoothing, it should be small relative to actual diffusion (self.viscosity)
-        self._v_projector.smoothing = 0
+        # If we add smoothing, it should be small
+        self._v_projector.smoothing = 1.0e-6
 
     ## This function is the one we will typically over-ride to build specific solvers.
     ## This example is a poisson-like problem with isotropic coefficients