HI, Are you elements either side of the domain periodic (i.e. along the cylinder axis)? This error comes up when a triangular face is not aligned so that the top singular vertex is at the same location. In this case direction 1 (bottom) edge is aligned to one of the other edges (dir2). If the two sides are periodic you might need to use the peralign option in NekMesh to get these faces aligned. Cheers, Spencer. From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Wang Tongkuai <3180102312@zju.edu.cn> Date: Wednesday, 8 May 2024 at 16:42 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] (no subject) This email from 3180102312@zju.edu.cn 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. 从 Windows 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>发送 Dear All, I meshed a cylinder with hexas and prisms at gmsh with no error. Here is the problem occurred when I NekMesh it: Orientation of triangular face (id = 10638) is inconsistent with face 3 of prism element (id = 3588) since Dir2 is aligned with Dir1. Mesh setup needs investigation terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError' I don’t know which surface is face 3 and how does the inconsistency happen. Dir 1 and Dir 2 are x- and y-axis direction, right? A half of y-z plane is shown. [cid:image003.png@01DAA19F.99577A90] Regards, Tongkuai.