Hi Xiangjun, From my experience of computing airfoil flow, the leading mode maybe different if your base flow is not well converged. If you compare the eigenspetrum, I believe you will find there is no big difference. I think you can try a higher oder calculations or different Krylov space. Regards, Wei On 18 Feb 2022, at 08:54, shan xiangjun <x_j_shan@outlook.com<mailto:x_j_shan@outlook.com>> wrote: This email from x_j_shan@outlook.com<mailto:x_j_shan@outlook.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. Hi Everyone, For 2D direct stability analysis of Nektar + +, when raising the NumSteps, I get different eigenvectors and I'm not sure which is correct (as shown in the figure). TimeStep = 0.004 TimeStep = 0.004 NumSteps = 4250 NumSteps = 8250 <74181780A2BD44EFB8F01C3554F38D2E.png> <872686C9FAC945B3B3D059AE5B7BA221.png> Why does NumSteps affect the results and how do I set its value? Looking forward to your reply! Best regards, Xiangjun Shan 从 Windows 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>发送 _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users