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-   -   Error in solution using "Grid Interface" (http://www.cfd-online.com/Forums/fluent/122763-error-solution-using-grid-interface.html)

agustinvo August 27, 2013 13:05

Error in solution using "Grid Interface"
 
3 Attachment(s)
Hi everyone!

I have the next problem

I'm simulating a duct, wich has an element at his upper side, who receives an amount of heat. Due to the shape of the internal elements of the duct, I had to mesh it in other file, and I've joined it using "Grid interface". I attach an image to explain the cross-section (scheme.png). I'm meshing twisted tapes inside ducts in order to see the heat transfer, how it is enhanced... for this reason, it is possible to see 5 zones inside the scheme:
  • Upper element
  • Duct
  • Tape, which separates the fluid into two zones
  • Two fluid zones

I can run the case, but it could happen two things:
  • I have cells, near to the grid interface, who have more temperature than the rest of the fluid and the duct (error1.png)
  • One of the fluid zones rests cold, and the other one get warmed. the upper element becomes crazy (error2.png).

I don't know where the problem is. I create the interface ant it happens. I think it has to be the union between the faces, but I've tried to increase the number of cross-section along the tube, but with no good news.

At first place, I run Fluent to create the grid interface, and I close it. After, I run it again to simulate. This is the load of the 2nd time:
Code:

> rc d7p21t0.35_tube.weld.cas.gz

Multicore processors detected. Processor affinity set!

Reading "| gunzip -c \"d7p21t0.35_tube.weld.cas.gz\""...
  ..........................................................................................

 3008880 hexahedral cells, zone  2, binary.
  449280 hexahedral cells, zone  3, binary.
  972000 hexahedral cells, zone 28, binary.
 1836000 hexahedral cells, zone 29, binary.
 1208160 quadrilateral interior faces, zone  1, binary.
  498694 quadrilateral interior faces, zone  8, binary.
  74464 quadrilateral interior faces, zone 12, binary.
 8382600 quadrilateral interior faces, zone 14, binary.
  161100 quadrilateral interior faces, zone 20, binary.
  304300 quadrilateral interior faces, zone 26, binary.
 2592000 quadrilateral interior faces, zone 27, binary.
 5075640 quadrilateral interior faces, zone 30, binary.
  112320 quadrilateral wall faces, zone  7, binary.
    416 quadrilateral wall faces, zone 10, binary.
    416 quadrilateral wall faces, zone 11, binary.
  112320 quadrilateral wall faces, zone 15, binary.
  143640 quadrilateral wall faces, zone 16, binary.
    900 quadrilateral wall faces, zone 18, binary.
    900 quadrilateral wall faces, zone 19, binary.
  18360 quadrilateral wall faces, zone 21, binary.
  18360 quadrilateral wall faces, zone 22, binary.
  216000 quadrilateral wall faces, zone 23, binary.
    1700 quadrilateral wall faces, zone 24, binary.
    1700 quadrilateral wall faces, zone 25, binary.
  18360 quadrilateral wall faces, zone 31, binary.
    2786 quadrilateral pressure-outlet faces, zone  4, binary.
    2786 quadrilateral velocity-inlet faces, zone  5, binary.
  172800 quadrilateral interface faces, zone  6, binary.
  17280 quadrilateral interface faces, zone  9, binary.
  162000 quadrilateral interface faces, zone 17, binary.
  112320 shadow face pairs, binary.
  18360 shadow face pairs, binary.
 6765743 nodes, binary.
 6765743 node flags, binary.

Parallel variables...
Building...
    grid,
        auto partitioning mesh by Principal Axes,
        distributing mesh
                pairs................,
                parts................,
                faces................,
                nodes................,
                shadow nodes................,
                cells................,
    materials,
    interface,
    domains,
        mixture
    zones,
        default-interior:001
        default-interior
        secctape
        extrtapein
        extrtapeout
        tape_in
        seccfluid
        lamina
        fluid_in
        entrada
        salida
        lamina-shadow
        default-interior:030
        default-interior.1
        seccweld
        extrweldin
        extrweldout
        weld_lateral
        weld_abs
        weld_out
        secctube
        extrtubein
        extrtubeout
        tube_in
        tube_out
        weld_out-shadow
        wall-35
        wall-34
        wall-36
        wall-33
        Skipping zone wall-33-shadow (not referenced by grid).
        wall-32
        Skipping zone wall-32-shadow (not referenced by grid).
        twisted
        fluido
        welding
        tubo
    grid interfaces,
        creating wall-33-shadow
        creating wall-32-shadow
    parallel,
    shell conduction zones,
Done.


Can you help me?

jb pouillard June 28, 2014 13:45

I have the same problem and don't understand it !!!
 
Hi augustin ,

did you find a solution to your problem , I have the same problem and don't understand it !!!

agustinvo June 28, 2014 19:36

Hi!

Sorry, but I couldn't solve this problem. I think the best idea is to mesh all together. If you can mesh it allntogether by using another tool you would avoid this problem, otherwise I don't know how to do it.

Good luck!

jb pouillard June 29, 2014 09:05

Ok thanks for the answer, for information i have several part in my mesh and i achieved one assembly without problem.
after that i separate my assembly to change only one part, the problem occured during this step , i thougth it was a problem of cell separation !
:confused:

jorkolino January 20, 2015 13:03

Quote:

Originally Posted by agustinvo (Post 448348)
Hi everyone!


wall-35
wall-34
wall-36
wall-33
Skipping zone wall-33-shadow (not referenced by grid).
wall-32
Skipping zone wall-32-shadow (not referenced by grid).
............
.............
grid interfaces,
creating wall-33-shadow
creating wall-32-shadow
parallel,
shell conduction zones,
Done.[/CODE]

Can you help me?


Hi, can you explain what is the shape of the walls that you stitch with grid interface? I dont get it from the first figure. More to say, I am worried about skippin these 33 and 32 shadow walls at the second file read. Your interface surface probably contains inner loops that somehow fluent cannot handle. Can you check if this is your case?


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