[Nek5000-users] nek and visit vy trouble

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

Hi Aleks, thanks for your answer.

I understand that Visit interpolates. I computed vorticity with  
comp_vort3, I replaced the temperature with the computed vorticity and  
I viewed it in VisIt.
What I don't understand it's the fact that the y component of the  
velocity changes sign, but the magnitude is the same. In this way,  
volume integrations during nek simulations are wrong, while  
integrations on tecplot with the output field files are correct.

How can it be possible?

Mario


Quoting nek5000-users at lists.mcs.anl.gov:

> Yes, Mario, as far I know, VisIt uses linear interpolation and  
> finite difference derivatives so when I look at the vorticity I  
> either use postnek or compute them in usrchk() with, say,  
> comp_vort3() and dump as a separate field sequence with outpost()  
> and then view them in VisIt
>
>
> Aleks
>
> ________________________________
> From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on  
> behalf of nek5000-users at lists.mcs.anl.gov  
> <nek5000-users at lists.mcs.anl.gov>
> Sent: Tuesday, October 10, 2017 8:52:50 AM
> To: nek5000-users at lists.mcs.anl.gov
> Subject: [Nek5000-users] nek and visit vy trouble
>
> I'm trying to make some volume integrals of the vorticity in the flow
> domain. I'm considering a two-dimensional plunging flat plate, in the
> body frame.
> Is it possible that variables accessed in nek, such as vy, are different
> from the one displayed in visit?
> I mean, in the fld file, and in the usr, vy has a sign, while in visit
> has the opposite sign.
> Furthemore, exporting the field files in tecplot format and performing
> integrations in tecplot, computation goes well.
>
> What's happening?
>
> Thank you
>
> Mario
>
> --
> Mario Ostieri
>
> Ph.D. Student
> University of Naples Federico II
> Department of Industrial Engineering
> Piazzale V. Tecchio 80
> 80125 Napoli, Italy
> tel. +390817682184
> email: mario.ostieri at unina.it
>
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>



Mario Ostieri

Ph.D. Student
University of Naples Federico II
Department of Industrial Engineering
Piazzale V. Tecchio 80
80125 Napoli, Italy
tel. +390817682184
email: mario.ostieri at unina.it