dolfin team mailing list archive

[Nuno David Lopes <ndl@xxxxxxxxxxxxxx>]

On Monday 05 May 2008, Anders Logg wrote:
> On Mon, May 05, 2008 at 03:38:49PM +0200, Ola Skavhaug wrote:
> > Ola Skavhaug skrev den 05/05-2008 følgende:
> > > >
> > > > I think the problem may be that it's not possible to plot a mesh
> > > > function defined on the facets of a mesh. Viper can't handle that as
> > > > far as I remember. It would be very good if this could be added since
> > > > it's a simple way to debug boundary conditions.
> >
> > Should be:
> >
> > bmesh = BoundaryMesh(mesh)
> > bmf = MeshFunction("uint", bmesh, bmesh.topology().dim())
> > #                                 ^^^^^
> > # use mesh-bmesh mapping to remap indicators and insert into bmf
> > plot(bmf)
>
> I think that's a good solution (to just add a few lines that extracts
> the boundary and then plots the cells of the boundary).

Thanks, I've got it!
After some copy paste and other extra lines for the markers, it's done. 


My c++ code for a boundary test.

int main()
{

  // Sub domain for heat inflow DirichletBC  
  class DirichletBC : public SubDomain
  {
    bool inside(const real* x, bool on_boundary) const
    {
      real h3=0.035;
      return ((x[0] > h3 - DOLFIN_EPS)&&(x[2]>DOLFIN_EPS)) && on_boundary;
    }
  };

  // {{{For boundary conditions debug
  class B_DirichletBC : public SubDomain
  {
    bool inside(const real* x,bool on_boundary) const
    {
      real h3=0.035;
      return ((x[0] > h3 - DOLFIN_EPS)&&(x[2]>DOLFIN_EPS));
    }
  };
  // }}}
 
  // Read mesh
  Mesh mesh("../barra4.xml");
  BoundaryMesh bmesh(mesh);

  MeshFunction<unsigned int> sub_domains(mesh, mesh.topology().dim() - 1);//
  MeshFunction<unsigned int> b_sub_domains(bmesh,    
            bmesh.topology().dim());//For boundary conditions debug
  
  // {{{ Mark all facets as sub domain 0 (*)
  sub_domains = 0; //interior and boundary facets
  b_sub_domains = 0; //facets of boundary mesh
  // }}}

  // {{{ Mark Dirichlet boundary as sub domain 1
  DirichletBC dirichletbc;
  B_DirichletBC b_dirichletbc;

  dirichletbc.mark(sub_domains, 1); //boundary facets of 3D mesh
  b_dirichletbc.mark(b_sub_domains, 1);//facets of boundary mesh
  // }}}

  // {{{ Save sub domains to file
  // The information we need to the main code
  File file("bc_subdomains.xml");
  file << sub_domains;
  // }}}
  
  // {{{ Plotting for boundary conditions debug 
  File b_file("bmf.xml");
  b_file << b_sub_domains;
  File bmfvtk("bmf.pvd"); 
  bmfvtk<<b_sub_domains; 
  plot(b_sub_domains);
  // }}}
}


-- 
Nuno David Lopes

e-mail:ndl@xxxxxxxxxxxxxx        (FCUL/CMAF)
           nlopes@xxxxxxxxxxxxxxx    (ISEL)
http://ptmat.ptmat.fc.ul.pt/%7Endl/