I've tried running this code following your instructions:
from dolfin import *
from mshr import *
geom=Rectangle(dolfin.Point(0.0,0.0),dolfin.Point(50.0,50.0))
mesh=generate_mesh(geom,100,"cgal")
class Axis42(SubDomain):
def inside(self, x, on_boundary):
return near(x[0], 42.0)
facets = FacetFunction('size_t', mesh)
facets.set_all(0)
Axis42().mark(facets, 2)
for i in range(len(facets.array())):
if facets.array()[i]==2:
print ("marked")
the compiler returns no print; if I change line 9 in
return near(x[0],0.0)
the mark method works, and facets.array() is not equal to 0 for all i.
Really thank you for your help.
Regards
SC
Il 11/12/2014 14:58, Jan Blechta ha scritto:
On Wed, 10 Dec 2014 20:24:08 +0100
simone <[email protected]> wrote:
Hi,
thank's for your support; i've tried using your code, that runs
without any error, but it still doesn't do what i need. The problem
is that with this definition of facets, the mark method of
LeftBoundary and RightBoundary objects (as defined in my first mail)
doesn't mark my domain. It is able to mark only parts of domain
boundary, not subdomain boundary (which is within the domain, not on
the boundary ), so if I try to integrate over subdomain boundary it
returns me 0.0 because there's no facet over which to integrate. I
suppose this problem is due to my implementation error, could you
please explain me where i'm wrong? Thank you
[please, keep [email protected] in CC]
1. ds = measure on exterior facets
dS = measure on interior facets
2. on_boundary in your SubDomains causes that it is only on boundary.
Example
class Axis42(SubDomain):
def inside(self, x, on_boundary):
return near(x[0], 42.0)
defines axis x=42.0 disregarding boundary.
Jan
Regards
SC
Il 10/12/2014 15:11, Jan Blechta ha scritto:
Hi,
we cannot find a problem why non-positive progress bar is to be
created and raising runtime error without a complete code to try.
But note that you are probably misusing SubMesh. Having solved some
problem on mesh and trying to integrate its solution around some
cells or facets is normally done without SubMesh. Like
u = Function(V) # V space on mesh
solve(..., u, ...)
facets = FacetFunction('size_t', mesh)
LeftBoundary().mark(facets, 2)
RightBoundary().mark(facets, 1)
# current syntax
F = u*ds(subdomain_id=1, subdomain_data=facets)
F += u*ds(subdomain_id=2, subdomain_data=facets)
# deprecated synatx
F = u*ds[facets](1)
F += u*ds[facets](2)
assemble(F)
i.e. everything is done on the orginal mesh and integration is
performed over on subset of original mesh using cell/facet markers.
No new mesh is ibtroduced using SubMesh, which just complicates the
things.
Jan
On Wed, 10 Dec 2014 02:19:13 +0100
simone <[email protected]> wrote:
Good evening,
i'm sorry if I rewrite to you but i cannot find a solution in the
forum neither in the documentation. I have a rectangular domain
and a smaller rectangular subdomain. After the resolution of a
differential problem over the domain, i need to evaluate the
integral of the obtained solution over the left and right sides of
the subdomain boundary. Called p the solution, this is part of my
code:
Gamma=FacetFunction("size_t",SubMesh(my_mesh,my_subdomain))
class LeftBoundary(SubDomain):
def inside(self, x, on_boundary):
return on_boundary and near(x[0],x1) #x1=x-coordinate of
the left side of the subdomain
class RightBoundary(SubDomain):
def inside(self, x, on_boundary):
return on_boundary and near(x[0],x2) #x2=x-coordinate of
the right side of the subdomain
Gamma.set_all(0)
LeftBoundary().mark(Gamma,2)
RightBoundary().mark(Gamma,1)
d_gamma=Measure("ds",domain=SubMesh(my_mesh,my_subdomain))[Gamma]
d_p=p*d_gamma(1)-p*d_gamma(0)
direction=assemble(d_p,exterior_facet_domains=Gamma)
If I try to run this code i get this error:
File "/usr/lib/python2.7/dist-packages/dolfin/cpp/mesh.py", line
4461, in mark
self._mark(*args)
RuntimeError:
***
-------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve
this issue *** using the information listed below, you can ask for
help at ***
*** [email protected]
***
*** Remember to include the error message listed below and, if
possible, *** include a *minimal* running example to reproduce the
error. ***
***
-------------------------------------------------------------------------
*** Error: Unable to create progress bar.
*** Reason: Number of steps for progress bar must be positive.
*** Where: This error was encountered inside Progress.cpp.
*** Process: unknown
***
*** DOLFIN version: 1.4.0
*** Git changeset: unknown
I cannot understand the meaning of the error message, so i don't
know how to modify the code.
I would like also to know what happens if the mesh vertexes don't
match the subdomain boundary, with the subdomain sides intersecting
mesh cells. I hope I've explained myself, I'm sorry for my english
Thank you for your support
Best regards
Simone Carriero
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