[enayath]

All,

I modeled 1/16 (22.5 degree) of my cylindrical domain (used periodic boundary condition). In Fluent, I am able to see the whole domain by going to "View" section as well as having the pressure distribution on my whole domain (pressure distribution is repeated every 22.5 degree)

I want to extract the pressure values on a surface of my domain and then apply that pressure distribution on a full surface of my full domain (the full domain that I have from the initial geometry before cutting it into 16 segments). How can I do it?

In Fluent, I tried to extract all points and pressure values. However, It does not let me. It is just a visualization feature and does not make any physical nodes in the text or CSV file.


Thank you in advance!

[LuckyTran]

It is indeed only a visualization feature. Only the 1/16th domain exists in Fluent and therefore you cannot extract the data on the entire domain.

If you are working in a csv, you can quite easily make a data mapper by mapping the coordinates and copying the data to the remaining 15 sectors.

But probably the solution you want is to build up the full sector in Fluent. You can do this with a sequence (x15) of mesh rotations and merging the resulting cell zones. You don't need to merge the boundaries or the interior boundary zones (it's definitely recommended not to merge the interior boundary zones because you'll likely hit an out-of-memory error). You might have to slit the periodic BC first.

[enayath]

Dear LuckyTran,

Thank you for your reply.

I could rotate the mesh. The question is how to merge the cell zones. I searched for it...No success...I think I should look for "Manage Cell Zones Panel " in FLUENT 16 or 18, but can not find it...any suggestion?

Also, when I rotate the mesh, do I need to save it as a new .cas file? In that case I will have 16 .cas files and then I need to append them (mesh-zone-append case/dat files). Am I right?


Regards,

[LuckyTran]

Yes, append case and data is your tool. Actually you might not eve need to merge anything, it depends how you want to work with the data but merging everything at least helps you think of the data the same way as before.

There's several ways to go about it. You can do 16 rotations and save them separately and then append them all together, that's one way.

Or you can rotate 22.5 degrees, append the original mesh. Rotate the whole (45 degree) thing another 22.5 degrees and append the original 22.5 degree mesh.

It's up to you, whichever you are more comfortable with.

In the GUI ribbon you go to "Setting up Domain", click combine, and in the types choose the fluid zones. You can also merge your boundaries likes walls, inlets, outlets etc. but do not merge the interior thingy. In the TUI you would use:

/mesh/modify-zones/slit-periodic
/mesh/modify-zones/fuse-face-zones blahblahblah
/mesh/modify-zones/merge-zones blahblahblah

I cannot remember whether you fuse the face-zones before the cell zones or vice versa.

[enayath]

LuckyTran,

Thank you for the information.

I see some difficulties when I want to do it and I appreciate if you could help me.

1- I have the original .cas and .dat file. If I want to get rid of interface mesh faces, I need to delete them in the case file, but when I want to save .cas and .dat files under a new name, it gives me an error. What can I do with it? Error: %create-sliding-interface: not a pairError Object: #f

2- If I do not open the dat file and just work with the case files and then delete the mesh interface section, it would be fine... It makes the all the boundaries and faces (8 cas files for 45 rotation each). However, when I want to export the data as ASCII file, FLUENT does not let me to export X-Y-Z coordinates as quantities. Another issue which this second approach is lacking of the fourth variable (like pressure) in the export quantities.

Can you please help me to understand the differences between these two steps?

Also, with regards to Combine, Merge-Merge zones...I just see wall and interface...there is not an option for me to select fluid zone.

Regards,

[LuckyTran]

You say some funny things which don't really make sense to me.


1) You shouldn't be deleting anything. But you should slit the periodic BC and save the case before you append. I don't know how to slit using the GUI, only using the slit-periodic TUI command. Question is why you are not able to slit the periodic pair, append, and merge?

2) You must append the case & data, otherwise there is not any data and hence you cannot export anything because there is nothing to export. I don't think you really need to specifically choose to export the x,y,z coordinates either because they should always be exported.

[enayath]

LuckyTran

So, here is an update from me.

I open my cas.file and then go to TUI.
I type mesh-modify-zones-slit-periodic
and then select my periodic ID and the software changes the periodic to symmetry. All pressure contours look ok.
Now, I save this modified version of my original cas.dat file with a new name.

When I open the new cas.dat file, I see this in TUI:
mesh interfaces,
Error: eval: unbound variable
Error Object: angular?

parallel,
Done.

So, it opens the new cas/dat file but all pressure values are wrong.

What am I missing when I use slit-periodic?

In the new cas.dat file:
I have "name"-periodic ---> symmetry
interface 1---> interface
interface 2---> interface
"name"-side1-wall-interface-1 ---> wall
"name"-side1-wall-interface-2 ---> wall

In the old cas.dat file:
I have "name"-periodic ---> periodic
interface 1---> interface
interface 2---> interface
"name"-side1-wall-interface-1 ---> wall
"name"-side1-wall-interface-2 ---> wall

I think I need to fix this before rotating the mesh. Correct?

Thank you!