[Nek5000-users] Wall flux contour plots in Visit

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

Hi Hank,

the "Isovolume" operator did the trick.

There is one oddity, though, which is that it seems to ignore the upper 
bound: i.e. when the wall faces have the scalar index 3, say, and 
another face type has 4, then the contour plot with isovolume between 
2.99 and 3.01 will appear on both faces 3&4. This is not a problem since 
I can just put all wall faces at the highest indicator value (4), but I 
thought it's somewhat peculiar.

Thanks for your help, the plots look real nice now.

Markus



nek5000-users at lists.mcs.anl.gov wrote:
> 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 
> <mailto: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 
> <mailto: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
>     <mailto: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>
>         <mailto: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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