Dear Stan and Wei,

 

Thanks a lot for your reply!

 

The XML files for base flow and stability analysis are attached.

 

I used the steady-state solver to calculate the base flow, and the resulting flow field is in the laminar flow state (the resulting file of base flow is also attached). Is it possible to ensure the convergence of the base flow in this way?

 

Regards,

 

Xiangjun Shan

 

 

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发件人: He, Wei <Wei.He@liverpool.ac.uk>
发送时间: Friday, February 18, 2022 6:23:35 PM
收件人: shan xiangjun <x_j_shan@outlook.com>
抄送: Nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk>
主题: Re: [Nektar-users] 2D direct stability analysis
 
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> wrote:

This email from 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 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
 
 
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