MeshFunction Refine

Question

Hi all,

http://fenicsproject.org/qa/44/mesh-refine-meshfunction
from the link above we know we can refine the mesh, which is equivalent to use high order function space.
But I have a problem about the MeshFunction refine. Suppose we do the following:

mesh=UnitSquareMesh(2,2)
mesh1=refine(mesh)
f=CellFunction("uint",mesh)
f.set_all(0)
f.array()[2:5]=1
f_refined = adapt(f,mesh1)

Traceback (most recent call last):
File "", line 1, in
File "/Applications/FEniCS1.2.app/Contents/Resources/lib/python2.7/site-packages/dolfin/cpp/fem.py", line 3572, in adapt
return _fem.adapt(*args)
RuntimeError:

*** -------------------------------------------------------------------------
*** Error: Unable to adapt mesh function.
*** Reason: Unable to extract information about parent mesh entites.
*** Where: This error was encountered inside adapt.cpp.
*** Process: 0
*** -------------------------------------------------------------------------

In the help file, the python support the syntax adapt(mesh_function, refined_mesh). I do not what goes wrong here. since in above asked question, they all have the same problems. Any help would be appreciated. Thanks.

Answer 1

Hi,
I think that there is some problem with the refine () function if it is called just with one argument.
In fact, if you do the following, it should work

from dolfin import *
mesh=UnitSquareMesh(2,2)
cell_markers = CellFunction("bool", mesh)
cell_markers.set_all(True)
mesh1=refine(mesh, cell_markers)
f=CellFunction("uint",mesh)
f.set_all(0)
f.array()[2:5]=1
f_refined = adapt(f,mesh1)

Comments

Funny, same answer in five minutes :D

Answer 2

Avoid using uniform refinement which does not set parent entities. Reported as issue 105.

mesh = UnitSquareMesh(2, 2)

cf = CellFunction('bool', mesh, True)
mesh1 = refine(mesh, cf)

f = CellFunction("size_t", mesh)
f.set_all(0)
f.array()[2:5] = 1
f_refined = adapt(f, mesh1)

Comments

Thanks a lot for answering, guys.