[samiahmed]

Hello,
I have a structured mesh around an object as shown in the first attached image.

Is there a way in topoSet or setSet utilities to select cells by number of layers from a wall. (e.g: in the figure below, select the third layer from the wall shown in green: see attached image).

Thanks

[JNSN]

I think there is no direct way. But you could try selecting first the faces belonging to the patch. Then grow this set three times. Do same for a second set, but grow only two times. Finally subtract second from first. Not tested but should work.

[HPE]

Hi,

- I think there is one topoSet can do this: haloToCell, which selects a specified number of layers, i.e. the entry of "steps".
- You need two subsequent haloToCell with "steps=2", and "steps=1", respectively. The first haloToCell (steps=2) will select the first two layers, and based on this haloToCell, another haloToCell (steps=1), the third layer only will be selected.

Hope this helps.

PS: Just out of curiosity, why do you wanna select the third layer only?

[samiahmed]

Could you please give me an example on how to use that?

I need to select the third layer because if that is possible I can create faceZones easily by the same approach (to create baffles, etc.).

[samiahmed]

Originally Posted by JNSN

I think there is no direct way. But you could try selecting first the faces belonging to the patch. Then grow this set three times. Do same for a second set, but grow only two times. Finally subtract second from first. Not tested but should work.

How to grow a set three time?

[JNSN]

Good question. This should do the trick:

actions
(
    
    // face set from patch
    {
        name    f0;
        type    faceSet;
        source patchToFace;
        action new;
        sourceInfo
        {
            name patchName;      
            action  new;
        }
    }

    // first layer cells
    {
        name    c0;
        type    cellSet;
        action  new;
        source     faceToCell;
        sourceInfo
        {
            set     f0;
            option  any;
        }
    }

    {
        name f0;
        type faceSet;
        source cellToFace;
        action new;
        sourceInfo
        {
            set c0;
            option all;
        }
    }


    // first and second layer cells
    {
        name    c0;
        type    cellSet;
        action  new;
        source     faceToCell;
        sourceInfo
        {
            set     f0;
            option  any;
        }
    }

);

[HPE]

Hi,

For `haloToCell` set, the following might be used as a guideline (haven't tested it):

actions
(
     // first layer
    {
        name    c1;
        type      cellSet;
        source   patchToCell;
        action new;
        sourceInfo
        {
            name <patchName>;
        }
    }

     // second layer
    {
        name    c2;
        type      cellSet;
        source   haloToCell;
        action    new;
        steps     1;
        sourceInfo
        {
            set    c1;
        }
    }

     // third layer
    {
        name    c3;
        type      cellSet;
        source   haloToCell;
        action    new;
        steps     1;
        sourceInfo
        {
            set    c2;
        }
    }

);

- Note that `topoSet` is a parallel executable. It may save you time depending on your case size.

Hope this helps.