Constant perturbation energy

[M. Y. Li]

Hi,

I am performing a linear stability analysis of a periodically grooved channel flow using Nek5000.

My workflow is as follows:

1. I first compute a base flow by running a fully nonlinear simulation for a sufficiently long time until the flow becomes steady.

2. I then perform a linear stability analysis following the approach used in the Nek5000 example lin_chan.

However, I observe that the perturbation energy does not change (neither growing nor decaying). Varying the Reynolds number also does not change this behavior. I am not sure what causes it.

I have attached my .usr and .par files for reference.

Any suggestions would be greatly appreciated.

Best regards,

M. Y. Li