dolfin team mailing list archive

[Andy Ray Terrel <aterrel@xxxxxxxxxxxx>]

AFAIK The meshfunction description of the BC doesn't allow this (the
user_subdomain is cast to 0).

Is it required to use pointwise eval of your subdomain.  This is
usually better for when you want to mark something that won't be
counted as the boundary or a small number of points that are not in
the topological search (like lower dimension than a facet).  If you
are marking a mesh function then this should be all that is needed to
tell what points to call your BC functions on.  When you define the
function for applying the BC, it will still give you a point that you
can eval from your other mesh.

-- Andy

On Fri, Mar 26, 2010 at 5:33 AM, Patrick Riesen <priesen@xxxxxxxxxxxxxxx> wrote:
> hello,
>
> i'm under way of creating in-/outflow bc conditions by transferring a
> discrete 1D flow profile function onto a boundary subdomain of a 2D mesh. I
> marked the subdomain by a meshfunction and use an expression in which i
> evaluate the bcs values by extracting them from the 1D discrete solution as
>
> BCInFlowProfile::eval (Array<double>& values, const Array<double>& x) const
> {
>  [....]
>  velocity1Dprofile.eval(values, x_eval);
>  [....]
>
> }
> i want to use "pointwise" method for applying the bcs, so that the
> velocities evaluated and specified on the vertices, but i get
>
> dolfin/fem/DirichletBC.cpp:635: void
> dolfin::DirichletBC::compute_bc_pointwise(std::map<unsigned int, double,
> std::less<unsigned int>, std::allocator<std::pair<const unsigned int,
> double> > >&, dolfin::BoundaryCondition::LocalData&) const: Assertion
> `user_sub_domain' failed.
>
>
> is using DirichletBC "pointwise" with a meshfunction and a subdomain id not
> possible?
>
> regards,
> patrick
>
>
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