[Cartuns11]

Hello,

I have been working on a multiRegion model using snappyHexMesh. I created complex surfaces in stl format, these were closed and had good contacts, but after the snappyHexMesh process, between regions and even on faces-region to outside volume, there were extra domains with 1 or 3 cells......

I have seen some posts in the forum, which talk about this, but I haven't found the solution or the problem cause. May be, for complex geometries, the snappy has problems to approach on surface, I don't know......

Does anyone know some solution?

Thanks. Greetings.

[Cagatayemre]

Hello, Did you find a solution ?

[Cartuns11]

Hi,

(using OF+1606)
Yes! I solved this problem last month! ( coincidence)

The solution is how you name the control volume (==blockMesh volume) and the commands of "splitMeshRegion" application.


First step is to name the blockMesh. I threw blockMesh and snappyHexMesh without a name for the control volume/blockMesh and as consequence, splitMeshRegion named controlVolume as "domain0".....for default. So, blockMesh has to have a name and following codes show where you have to write name in the blockMeshDict ( in this case the name is "air":



Old:

vertices
(
    (2.7 -0.8 0.57)
    (2.95 -0.8 0.57)
    (2.95 -0.5 0.57)
    (2.7 -0.5 0.57)
    (2.7 -0.8 0.85)
    (2.95 -0.8 0.85)
    (2.95 -0.5 0.85)
    (2.7 -0.5 0.85)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (60 60 60) simpleGrading (1 1 1)
)

Solution:

vertices
(
    (2.7 -0.8 0.57)
    (2.95 -0.8 0.57)
    (2.95 -0.5 0.57)
    (2.7 -0.5 0.57)
    (2.7 -0.8 0.85)
    (2.95 -0.8 0.85)
    (2.95 -0.5 0.85)
    (2.7 -0.5 0.85)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) air (60 60 60) simpleGrading (1 1 1)
)

And the last step consists in which commands are introduced in the splitMeshRegion line:


Old:

 splitMeshRegions -cellZones

This command splits all regions = all cellZones, incluiding domain0, domain1, ......domain2345

Solution:

 splitMeshRegions -cellZonesOnly

This command only splits the cellZones which are named by the user.


Using these steps, I haven seen the extra domains anymore.

I hope this explanation is useful for you.

[Cagatayemre]

Thank you my friend. I also have found a solution to this problem. I have changed the location in mesh coordianates.

There were more than one locations in mesh and. I think that was the problem.


Solution was to put just one location inside the small geometry

Originally Posted by Cartuns11

Hi,

(using OF+1606)
Yes! I solved this problem last month! ( coincidence)

The solution is how you name the control volume (==blockMesh volume) and the commands of "splitMeshRegion" application.


First step is to name the blockMesh. I threw blockMesh and snappyHexMesh without a name for the control volume/blockMesh and as consequence, splitMeshRegion named controlVolume as "domain0".....for default. So, blockMesh has to have a name and following codes show where you have to write name in the blockMeshDict ( in this case the name is "air":



Old:

vertices
(
    (2.7 -0.8 0.57)
    (2.95 -0.8 0.57)
    (2.95 -0.5 0.57)
    (2.7 -0.5 0.57)
    (2.7 -0.8 0.85)
    (2.95 -0.8 0.85)
    (2.95 -0.5 0.85)
    (2.7 -0.5 0.85)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (60 60 60) simpleGrading (1 1 1)
)

Solution:

vertices
(
    (2.7 -0.8 0.57)
    (2.95 -0.8 0.57)
    (2.95 -0.5 0.57)
    (2.7 -0.5 0.57)
    (2.7 -0.8 0.85)
    (2.95 -0.8 0.85)
    (2.95 -0.5 0.85)
    (2.7 -0.5 0.85)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) air (60 60 60) simpleGrading (1 1 1)
)

And the last step consists in which commands are introduced in the splitMeshRegion line:


Old:

 splitMeshRegions -cellZones

This command splits all regions = all cellZones, incluiding domain0, domain1, ......domain2345

Solution:

 splitMeshRegions -cellZonesOnly

This command only splits the cellZones which are named by the user.


Using these steps, I haven seen the extra domains anymore.

I hope this explanation is useful for you.