Dear Bruno
Thank you so much for your reply, It was very helpful. Regarding the mass
lumping question, I just compute it as follows:
for(unsigned int q_index = 0 ; q_index < n_q_points ; ++q_index)
{
double lump = 0.0;
for(unsigned int i = 0; i<dofs_per_cell; ++i)
for(unsigned int j = 0; j<dofs_per_cell; ++j)
lump += fe_values.shape_value(i, q_index) *
fe_values.shape_value(j, q_index) *
fe_values.JxW(q_index);
lump_cell_matrix(i,i) = lump;
}
or another way can be
for(unsigned int q_index = 0 ; q_index < n_q_points ; ++q_index)
{
for(unsigned int i = 0; i<dofs_per_cell; ++i)
for(unsigned int j = 0; j<dofs_per_cell; ++j)
if(i==j)
lump_cell_matrix(i,j) += fe_values.shape_value(i, q_index)*
fe_values.JxW(q_index) ;
else
0;
}
but I am not sure if it always works, what if I want to use Q2, I feel like
it's not correct. I would be happy to hear your opinion or advice.
Regards
Shahin
On Thu, May 20, 2021, 14:49 Bruno Turcksin <bruno.turck...@gmail.com> wrote:
> Shahin,
>
> I think this does what you want
> https://dealii.org/current/doxygen/deal.II/namespaceGridTools.html#addb822f0e3068e48640ecc981ee6c1e6
> I am not sure I understand what's your question about lumping.
>
> Best,
>
> Bruno
>
> On Thursday, May 20, 2021 at 4:11:47 AM UTC-4 sh1990....@gmail.com wrote:
>
>> Dear all
>> Hello, hope you are safe and healthy.
>>
>> I am trying to use deal.ii for my work but I have encountered some
>> difficulties during implementation and I would highly appreciate it if you
>> can help me with it.
>>
>> I want to use flux corrected transport scheme, and for this I should go
>> through all the neighbouring of a certain node and compute the fluxes to
>> that node, there is also a flux limiter which is depend on this flux, so I
>> can't go cell by cell as many of the tutorial in dealii has suggested,
>> instead I need to go through a patch consist of all neighbouring cells, now
>> I am just wondering whether there is any class in dealii which can do this
>> process, I would really appreciate any help and feedback from you.
>>
>> On the other hand there is a part in which I should compute a lump matrix
>> and add it to the scheme, but I feel like this is also wrong and should not
>> be done over a cell(please see the attachment).
>>
>> I am trying to implement some initial conditions, whenever I run each
>> part of the code separately I can get the picture but when I am trying to
>> put it all together in a loop it won't work (please see the attachment). I
>> would be thankful if you could let me know how I can fix it.
>>
>> I am looking forward to hearing from you.
>> Sincerely
>> Shahin Heydari
>>
>> --
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