Hi,
I want to refine a mesh and the correspondent boundary markers.
The code gives no error but the boundary markers saved as .pvd files (and visualized in Paraview), after the adapt command have very large values and they do not correspond at all to the non adapted markers. I am using 2019.2.0.dev0.
Here a minimal working example:
from dolfin import *
parameters["refinement_algorithm"] = "plaza_with_parent_facets"
class Top(SubDomain):
def inside(self,x,on_boundary):
return on_boundary and x[1] > 1.0-1e-10
mesh = UnitCubeMesh(2,2,2)
d = mesh.topology().dim()
boundaries = MeshFunction("size_t", mesh, d-1)
boundaries.set_all(0)
top = Top()
top.mark(boundaries,1)
mesh1 = adapt(mesh)
boundaries1 = adapt(boundaries, mesh1)
File("cube_boundaries.pvd") << boundaries
File("cube_boundaries_refined.pvd") << boundaries1
The issue is that when refining the mesh, new facets are introduced into the mesh (that had no previous parent facet, as they are internal to a cell, these facets get large numbers as values.
I would like to note that your example is a very good one (good way of presenting a minimal working example), but I have simplified it slightly for easier visual interpretation:
from dolfin import *
parameters["refinement_algorithm"] = "plaza_with_parent_facets"
class Top(SubDomain):
def inside(self,x,on_boundary):
return on_boundary and x[1] > 1.0-1e-10
mesh = UnitSquareMesh(2,2)
d = mesh.topology().dim()
boundaries = MeshFunction("size_t", mesh, d-1)
boundaries.set_all(0)
top = Top()
top.mark(boundaries,1)
mesh1 = adapt(mesh)
boundaries1 = adapt(boundaries, mesh1)
File("cube_boundaries.pvd") << boundaries
File("cube_boundaries_refined.pvd") << boundaries1
In the following picture, the left figure is the adapted mesh (with the value==1 marked as a bolder line), and the RHS the original mesh (with similar bold marking).
As you can see, facets that original belonged to a facet has kept its marker, but new ones have gotten an arbitrary large value.
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