code_saturne User's Forum

Hello,

I know that with v6 the CDO algorithm has been added for mesh displacement in ALE simulations.
If I want to impose a given velocity on a moving boundary (using the "fixed velocity" ALE-BC option), but the velocity is not constant for all the cells/nodes of the boundary, is there the possibility of imposing the velocity directly to the nodes?
I.e., looping on "nodes" and define (as a function of the position) their velocity?

Thank you very much for your help.
Best regards,
Daniele

Hello,

I wrote this post too early: I found the answer in the cs_user_boundary_conditions_ale.f90 example!
Is there the possibility to use the C language cs_user_boundary_conditions.c to specify the ALE boundary conditions?
As far as I understand, code_saturne provides C syntax to perform vectors/matrix operations, whereas this is not possible in Fortran.

Thank you very much.
Best regards,
Daniele

Hello,

Yes, I believe is should be possible to use cs_user_boundary_conditions.c to specify the ALE boundary conditions, though there are no examples yet.

Actually, we are not adding too many C examples for boundary conditions yet, because we are in the process of allowing boundary definitions in C using the same mechanism as for CDO (work in progress). So we do not want to push users to change their user code when another change will soon follow. But it is possible if you need it for other reasons.

In "legacy" mode, I do not believe it is possible to prescribe values directly at nodes, though I may need to check. In CDO, the equation is solved at nodes instead of cells, so it should be possible, unless there are other constraints that I am not aware of. But I do not have an example for that yet. I would need to check with colleagues who worked on that (I'll suggest to them to read your post).

Best regards,

Yvan