[Nek5000-users] Small random perturbations

[nek5000-users at lists.mcs.anl.gov]

Hello everyone 

I have been troubled by the exactly same problem with Ali for the last two months with the turbulent channel case. When I increase elements, the flow is laminarized even though the Re is quite big (10000). I tried many different ways. Even added a constant random forcing, but the disturbance just disappear. (because the disturbance shape is not the same as that in linear stability theory, it is possible that the disturbance just decay. ) 

How I finally solve this problem is running a coarse mesh calculation first, and then interpolating the result to fine mesh. Then I got a sustaining turbulence and the result is quite satisfying. I hope this could solve Ali's problem. 

However, I still cannot understand why increasing resolution would laminarize flow. hoping someone else could explain the problem. 

Regards 

Bien cordialement 

Zhenrong JING 

Doctorant (Doctor Candidate) 

LHEEA 

Ecole Centrale de Nantes 

1 Rue de la Noë, 44321 Nantes, France 
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