Hello Kaloyan Kirilov, I want to start by using GMSH to NEKTAR, and then use the peralign module in Nekmesh to align p1 and p2 for rotational periodicity. To pinpoint the problem, I have simplified the mesh to its most basic test state. However, no matter what I try, I am unable to achieve the aforementioned requirements using NekMesh -m peralign; it always results in errors. Assuming thi .geo file corresponds to a 2D mesh named test.msh, my operations are as follows: NekMesh test.msh test.xml:xml:uncompress NekMesh -m peralign:surf1=5:surf2=6:dir=z:rot=PI/6 test.xml test_p.xml Subsequently, an error occurs: [ProcessPerAlign] WARNING: Could not find matching edge for surface element 3. Skipping periodic alignment. I hope I have made myself clear. Thank you for your assistance. Best regards, Yaguang. -----原始邮件----- 发件人:"Vivarelli, Guglielmo A" <guglielmo.vivarelli12@imperial.ac.uk> 发送时间:2024-04-14 19:30:07 (星期日) 收件人: "谢亚广" <xieyaguang@iet.cn>, nektar-users <nektar-users@imperial.ac.uk> 抄送: 主题: Re: [Nektar-users] Questions about the plane of rotational periodic symmetry Hi Yaguang, I am not too sure of what you are trying to do, do you just want the two curves to match periodically and then convert the mesh from GMSH to Nektar? If you give me a little more info I may be able to help you. All the best, Guglielmo From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of 谢亚广 <xieyaguang@iet.cn> Sent: 13 April 2024 05:00 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Questions about the plane of rotational periodic symmetry | This email from xieyaguang@iet.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 to disable email stamping for this address. | Hello Kaloyan Kirilov, Thank you very much for providing those solutions. Unfortunately, I am still encountering the same error. I generated the mesh using gmsh, and for testing purposes, I simplified the mesh to the most basic case. Here is the content of the .geo file: SetFactory("OpenCASCADE"); Circle(1) = {0, 0, 0, 4, 0, Pi/6}; Circle(2) = {0, 0, 0, 14, 0, Pi/6}; Line(3) = {2, 4}; Line(4) = {1, 3}; Curve Loop(1) = {3, -2, -4, 1}; Plane Surface(1) = {1}; Transfinite Curve {3, 4} = 3 Using Progression 1.1; Transfinite Curve {1, 2} = 3 Using Progression 1; Transfinite Surface {1}; Recombine Surface {1};//+ Physical Curve("p1", 5) = {3}; Physical Curve("p2", 6) = {4}; Physical Curve("up", 7) = {1}; Physical Curve("up2", 8) = {2}; Physical Surface("plane", 9) = {1}; In this file, I want "p1" and "p2" to represent the periodic boundaries for rotation. Thank you once again for your guidance. Best regards, Yaguang.