[Nek5000-users] Pipe Roughness

[nek5000-users at lists.mcs.anl.gov]

Hi Ali,

Regarding Nek-Nek, this might be helpful:

http://nek5000.github.io/NekDoc/tutorials/neknek.html

Regarding your question in one of your previous messages: the key aspect in coupling two meshes in a NekNek calculation is the boundary condition of the surfaces that overlap another domain... these surfaces must have ‘int’ boundary condition. At the beginning of the calculation, this serves as the flag for the solver to identify the surface GLL points that overlap with another domain. These surfaces become Dirichlet surfaces from there on, where Dirichlet velocity data is obtained by interpolating solution (velocity and passive scalars) between domains at the end of each time-step and during sub-iterations (number of sub-iterations at each time-step are controlled by the parameter ngeom specified in usrdat).

Take a look at this tutorial, and see if it helps make things clear.. You can also look at the article “A spectrally accurate method for overlapping grid solution of incompressible Navier–Stokes equations”.
If you still have questions, please let me know. Should you choose to use NekNek for this calculation, I can help you setup the problem/mesh.

Ketan



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