Anders Logg wrote:
> On Mon, Mar 31, 2008 at 07:15:23PM +0200, Murtazo Nazarov wrote:
>
>> Anders Logg wrote:
>>
>>> On Mon, Mar 31, 2008 at 03:52:57PM +0200, Murtazo Nazarov wrote:
>>>
>>>
>>>> Hi,
>>>>
>>>> I want to apply a boundary condition to the vertices on a boundary. For
>>>> that I define:
>>>>
>>>> // Sub domain for MyBC
>>>>
>>>> class MyBC_Boundary2D : public SubDomain
>>>> {
>>>> public:
>>>> bool inside(const real* p, bool on_boundary) const
>>>> {
>>>> return on_boundary && (p[0] < xmax - bmarg) && (p[0] > xmin + bmarg);
>>>> }
>>>> };
>>>>
>>>> Then I initialize:
>>>> //-----------------------------------------------------------------------------
>>>>
>>>> void MyBC::init(SubDomain& sub_domain)
>>>> { ...
>>>> mesh.init(0);
>>>> sub_domains = new MeshFunction<uint>(mesh, 0);
>>>> ...}
>>>>
>>>>
>>> Do you remember to set everything to 1 (number of subdomains) here?
>>>
>>>
>>>
>> Yes I do:
>>
>> // Mark everything as sub domain
>> 1
>> (*sub_domains) = 1;
>>
>>
>> // Mark the sub domain as sub domain
>> 0
>> sub_domain.mark(*sub_domains, 0);
>>
>> /murtazo
>>
>
> Then I have no idea. You just need to dig into the code and see what
> goes wrong.
>
>
I think I found a mistake in Subdomain.mark(). The thing is bool
on_boundary should be defined
inside the loop for computing subdomain marker:
// Always false when not marking
facets
//bool on_boundary =
false;
// Compute sub domain
markers
for (MeshEntityIterator entity(mesh, dim); !entity.end(); ++entity)
{
bool on_boundary = false;
...
}
Otherwise, if you want to apply a boundary condition on vertices, it
becomes always
true after once meeting a vertex on the boundary.
It solved problem for me.
/murtazo
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