[Nek5000-users] Compute the derivatives

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

Are you viewing derivatives computed w/ nek, and then dumped
and visualized by VisIt?  Or are these derivatives computed
inside one of the vis packages? (don't know if that's even
possible...)

If you are well-resolved, derivatives will appear continuous.
If you are marginally resolved, they may or may not appear
continuous, since the underlying basis is only C0.

One option is, say,

       call gradm1(tx,ty,tz,t)
       call dsavg(tx)
       call dsavg(ty)
       call dsavg(tz)

which would project appropriately declared arrays tx,ty,tz 
into C0 --- it does not always make things look better, but 
often does.  Also, it will make visit happy since Visit expects 
to visualize C0 fields.

hth

Paul

On Tue, 8 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:

> Hi all,
>
> Thanks for the tip Aleks.
> Anyway, I have another question. When I visualize the computed derivatives 
> using VisIt or Tecplot, it appears that discontinuities exist at the 
> interfaces between elements.
> Is that normal or did I screw up something when setting up the calculation ?
>
> Thanks,
>
> JC
>
> PS: Attached is a small portion of my computational domain on which one can 
> clearly see the discontinuities.
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