Hi Markus,
the problem is diffusion of the light in multi-layers translucent materials.
so between the layers I mean after getting the computations in the first layer
for example, we need a continuty condition so the next conditions are needed
u_2 = \frac{n_1}{n_2} u_1 .............(1)
\frac{\ ptl u_2 }{\ptl z}= \frac{D_1}{D_2}\frac{\ ptl u_1 }{\ptl z}
..............(2)
where n_1, n_2 are the refractive index of the first and the second layery resp.
D_1 ,D_2 are the diffusion constant of the first and the second
layery resp.
the second boundary condition refers to that the flux on the boundary from the
first side (which one can comute it depending on the computations in the first
layers after postprocessing the solution in the first layer) is equal to the
flux on the same boundary but in the other side.
I do not know whether one can neglict it from the computation .....
best regards,
ahmad
________________________________
Von: Markus Bürg <[email protected]>
An: [email protected]
Gesendet: 6:48 Dienstag, 16.August 2011
Betreff: Re: [deal.II] applying multiple boundary conditions in the same
boundary
Hello Ahmad,
how does it come that you want impose multiple boundary conditions on
one and the same boundary? I have never seen this before and I doubt
that this mathematically sound.
Best Regards,
Markus
Am 15.08.11 19:05, schrieb Ahmad Al Nabulsi:
hi all,
>
>I would like to ask whether it is possible to implement neumann
boundary condition and dirichlet boudary condition to the same boundary.
>
>
>I tried it but unfortunately it did not fulfilled, I mean that
dirichlet boundary condition was fulfilled but neumann wasn't. I
checked neumann from the derivative of the solution.
>
>
>I used for dirichlet the same as in the examples:
>
>
> {
> std::map<unsigned int,double> boundary_values;
>
> VectorTools::interpolate_boundary_values (dof_handler,
> bi,
> *BC_Function,
> boundary_values);
>
> MatrixTools::apply_boundary_values (boundary_values,
> system_matrix,
> solution,
> system_rhs);
> }
>
>
>
>
>and neumann
>
>
>{
> double JxW = fe_face_values.JxW(q_point);
> for (unsigned int i=0; i<dofs_per_cell; ++i)
> cell_rhs(i) += ( neumann_val *
> fe_face_values.shape_value(i,q_point) * JxW);
> }
>
>
>
>
>
>
>any helful comments will be appreciated.
>
>
>
>best regards,
>ahmad
>
>
>
>
>
>
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