Seyed,
Is there a command that allows me to assign values to the DoF. Can you
please explain this a bit more.
The Gauss quadrature points never include the vertices [1] so saying
that the values represent forces for each vertex and at the same
time that the values are computed within Gauss points sounds
contradictory.
Yes, you are right. I described it a bit mixed up. The vector is just
shaped and designed for our global DoFs structure. You initialize it by:
|Vector<double> cell_cf(dofs_per_cell);
|
Of course integration points and vertices are different. Thanks for the
reference, it may come useful.
|Note that this approach is only suitable for Q1 elements. For higher
polynomial degree, you have to calculate the values for all the support
points of the finite element.
|
Would you suggest another approach? Since it may be useful to implement
this in a general way, useable for higher degrees of freedom.
@Jean-Paul:
Providing the theory is for our benefit (and therefore yours). No
one here is necessarily an expert in what you're trying to
accomplish. So, for all of your explanation, an equation or two
might go a long way to help us understand exactly what you're trying
to achieve and, therefore, help us suggest how you would accomplish
it. If you can't express your problem clearly then please don't be
surprised if you don't receive any meaningful assistance. Help us
help you.
Of course, but I just wanted to save you from additional headaches :)
But it doesn't work when we don't know what you want to do :-)
The computation of configurational forces is accomplished by the
following formula:
<https://lh3.googleusercontent.com/-B38RUw135-c/WIjDUOvqsfI/AAAAAAAAAEI/4rD24zbgMeoI9O-2MFpXt77UTbGAHjmLQCLcB/s1600/config_forces.png>
Deal.II does not attempt to be the beginning and end of provided
functionality. Yes, there are times when deal.II does not provide
some functionality that you require. There are a zoo of other
libraries that you could also use to extend your code and fill in
the gaps that deal.II does not provide. Of course, we always welcome
extensions to existing features (e.g the relatively
new CellDataStorage class
<https://www.dealii.org/developer/doxygen/deal.II/classCellDataStorage.html>
and TransferableQuadraturePointData
class
<https://www.dealii.org/developer/doxygen/deal.II/classTransferableQuadraturePointData.html>)
or the addition of new ones.
How can I use these new features? Is there a step example or tutorial?
Is this TransferableQuadraturePointData the same like in step-18?
Is this a deal.II error or a user error? Have you repopulate
the local_dof_indices vector for each new cell that you're doing
this "assembly" on? It looks like all contributions are going to a
fixed set of global DoFs.
I think more of a user error. Deal.II is nice and very elegantly
designed. I just don't think it will automatically assemble it correctly
in this case. First I have to understand it, before telling the program. ;)
Having read through this thread, I think that you are stuck because you
are familiar with one code and the corresponding notation, and you
expect that deal.II uses the same notation and does the same thing. So
you try to do in deal.II what you do there, but you can't find the same
terminology, the same functions, etc.
As an example:
I just did this:
|
std::vector<types::global_dof_index>local_dof_indices(dofs_per_cell);
typenameDoFHandler<dim>::active_cell_iterator cell
=dof_handler.begin_active(),endc =dof_handler.end();
for(;cell !=endc;++cell)
{
if(cell->is_locally_owned())
{
fe_values.reinit(cell);
...configurational forces computation ...
}
configurational_forces =cell_cf;
We don't know what "configurational forces" are. Or what, in your
formula, the various terms are.
I think that the only way to make progress is if you write down the
mathematics you want to implement, and then compare it with what the
various tutorial programs do. For example, for integrating the local
right hand side you may want to see steps 3 and 4, as well as 8. For how
exactly this interacts with hanging nodes, you may want to see step-6.
The point is that you need to expect to see similar mathematics, but
different terms than you are used to.
Best
W.
--
------------------------------------------------------------------------
Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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