CFD Online Discussion Forums - Error in solution using "Grid Interface"

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?