[Nek5000-users] Wall flux contour plots in Visit

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

Hi Markus,

VisIt makes the decision of what to keep hexahedron by hexahedron.  Since
you have a point-centered variable, it makes the decision for a hexahedron
by looking at all nodes incident to that hexahedron.  I think the blue cells
have some nodes that meet the criteria and some that don't (which are blue).

Another option is to try the "Isovolume" operator.  Rather than taking cells
from the input mesh without modifying them, it will subdivide cells that
partially meet the criteria and partially don't meet it.  This will
hopefully eliminate your blue region.

If that doesn't work, send me a picture and an email at hchilds at lbl.gov.  We
can iterate offline and spare the list and report back when we have it
solved.

Best,
Hank

On Sat, Jul 17, 2010 at 1:07 PM, <nek5000-users at lists.mcs.anl.gov> wrote:

> Hi Hank,
>
> that worked pretty well, thanks.
> One strange thing happens, though, which is that when I want to visualize
> contour plots on a cylinder surface, say, (where the surface is identified
> by some value of a scalar variable), the geometry turns "inside out", i.e.
> the outer cylinder wall, where the mesh connects to, is colored constant
> blue, but the inner wall, which faces "nothing", has the contour plotted on
> it. When I switch from natural/nodal to zonal, it works but the values are
> all about half of what they used to be. Which value is correct? And how can
> I get natural/nodal plots on the correct side of a face?
>
> Thanks,
> Markus
>
>
>
> nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hi Markus,
>>
>> Sure.  If you make a new field, "identifier", then you would make a
>> Pseudocolor plot of heat flux and apply the Threshold operator to it.  You
>> would then tell the Threshold operator to threshold by "identifier" (not
>> heat flux" and that you only wanted values between 0.99 and 1.01 (for the
>> wall faces).
>>
>> HTH!
>> -Hank
>>
>> On Wed, Jul 14, 2010 at 1:20 PM, <nek5000-users at lists.mcs.anl.gov<mailto:
>> nek5000-users at lists.mcs.anl.gov>> wrote:
>>
>>    Howdy VisIt-eers among the Neks,
>>
>>    I'd like to visualize certain wall values (heat flux, say) in VisIt.
>>    Is there a way to extract the boundaries from the complete nek
>>    domain in VisIt and then plot certain values only on them?
>>    What might help with this is that I can create an identifier
>>    variable which would be 1, say, on all wall faces, 2 on all
>>    periodic, etc. (see post from Thu Feb 4.)
>>
>>    Thanks for any help,
>>    Markus
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