Hi Alexander, The standards steps you would need to ensure are correct. 1. Have you explicitly stated in Gmsh that the surfaces 700 and 800 are periodic? 2. Try to add :abstol=1e-8 to the PerAlign call 3. If you still have the issue - please rename and send us the .msh and .geo to .txt. They are now filtered by Outlook. I have also just forwarded you the conversation Yaguang about the periodicities in case you cannot find it fully. Kind Regards, Kaloyan ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Alexander Schukmann <alexander.schukmann@protonmail.com> Sent: Monday, May 20, 2024 5:15 PM To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] NekMesh: Inconsistent triangular face orientation This email from alexander.schukmann@protonmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list<https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email stamping for this address. Hello everybody, I tried converting a 3D tetra/prism mesh (generated with gmsh) of a simple cylinder from msh to xml using NekMesh. The domain has periodic boundaries along the cylinder axis. However, I receive the following error: Orientation of triangular face (id = 113069) is inconsistent with face 3 of prism element (id = 55392) since Dir2 is aligned with Dir1. Mesh setup needs investigation terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError' I've seen a similar post from May 12th, where it was suggested to try the peralign option, so I used: NekMesh -m peralign:surf1=700:surf2=800:dir=z:orient CylReD3900.msh CylReD3900.xml with no success. The two surface IDs 700 and 800 of course refer to the periodic boundary faces. I attached my msh file and appreciate any help. All the best Alex Sicher versendet mit Proton Mail<https://proton.me/>.