[Nek5000-users] moving mesh and outlet BC

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

Dear Neks,

Here is a video from a contracting pipe that has an outlet BC on the non-moving side boundary. The code morphes the mesh, but the solution is not converged (message: Unconverged Helmholtz3/Mesh). The velocity direction correctly follows the moving boundary, but the pressure is switching only at a full cycle thus resulting in not being compliant with velocity direction every other ¼ cycle.

My guess is that the outlet boundary may not be suitable for incoming velocity resulting from the expansion stroke. Has anyone solved a similar problem and what is the best approach to take? Any advice is appreciated.

Thanks,
-emilian
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20161212/4dbec8c8/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2cycle.mpg
Type: video/mpeg
Size: 907264 bytes
Desc: 2cycle.mpg
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20161212/4dbec8c8/attachment-0001.mpg>