Identifying the face which requires communicated data for computation

[Vidyesh Dapse]

Hello everyone.
I am working on the discontinuous-Galerkin solver, which is described in tutorial step-76. In solver, time stepping is performed using the Low Storage Runge Kutta method. The stage-wise computation is performed using loop_cell_centric(). The solver uses MatrixFree class. I understood that computation is divided into 3 parts to make computation-communication overlap possible.

I want a method that can give me a flag indicating "whether a given face of a particular cell requires ghost data for computation of face integral?"

Thanks a lot in advance for suggestions!

[Wolfgang Bangerth]

On 4/20/23 02:57, Vidyesh Dapse wrote:
>
> I want a method that can give me a flag indicating "whether a given face of a
> particular cell requires ghost data for computation of face integral?"

This can only happen if you are on a locally owned cell and the neighboring
cell (across from the face you are considering) is a ghost cell. So the
condition would be
if (cell->is_locally_owned() && cell->neighbor(f)->is_ghost())
or something like this.

Best
W.

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Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/