Re: [deal.II] Adding rows on system matrix connecting to dof

[Wolfgang Bangerth]

On 04/15/2018 07:30 PM, Jaekwang Kim wrote:


and I think I should add this cell_matrix(i,j) and cell_rhs(i) to my system 
matrix.


Yes.


but not overlapping the rows that describe weakform of original poisson 
equation.. so I think i should not use them...




for (unsigned int i=0; i

[deal.II] Adding rows on system matrix connecting to dof

[Jaekwang Kim]

Hi, all 

I have a question on using deal.ii for solving unknown boundary condition 
problem. 
I have thought the most minimized related to my question. 

where I consider a navies slip boundary condition, and I have tried to 
solve this with finite difference.
For more demonstration please see following screenshot. 




Finite Difference Formulation might be...





where the last raw of matrix is added to show boundary condition at lower 
plate.

 

and I think problem is generally well posed so that I can solve this with 







Now, I am trying to solve same problem using finite element method...





The description of same boundary condition in weak form will look like 

 

 has on the boundary



for (unsigned int face=0; faceface(face)->boundary_id() == 2)

{  for (unsigned int q=0; q