CFD Online Discussion Forums - [blockMesh] Creating O-meshes

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)

- OpenFOAM Meshing & Mesh Conversion (https://www.cfd-online.com/Forums/openfoam-meshing/)

- - [blockMesh] Creating O-meshes (https://www.cfd-online.com/Forums/openfoam-meshing/69523-creating-o-meshes.html)

Creating O-meshes

Hi.

I need to make an O-mesh using blockMesh, is someone able to help me out?
I need it for an airfoil, but a cylinder-example or the like would be great.

Thanks a lot!

/Mads

There you go. This mesh has refinement towards both ends of the cylinder, so it could be simplified to use only five blocks.

Code:



FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    object      blockMeshDict;

}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //



convertToMeters 0.025;



vertices

(

    (0.21 0.21 0)

    (-0.21 0.21 0)

    (-0.21 -0.21 0)

    (0.21 -0.21 0)

    (0.21 0.21 1.2)

    (-0.21 0.21 1.2)

    (-0.21 -0.21 1.2)

    (0.21 -0.21 1.2)

    (0.353553 0.353553 0)

    (-0.353553 0.353553 0)

    (-0.353553 -0.353553 0)

    (0.353553 -0.353553 0)

    (0.353553 0.353553 1.2)

    (-0.353553 0.353553 1.2)

    (-0.353553 -0.353553 1.2)

    (0.353553 -0.353553 1.2)

    (0.21 0.21 0.6)

    (-0.21 0.21 0.6)

    (-0.21 -0.21 0.6)

    (0.21 -0.21 0.6)

    (0.353553 0.353553 0.6)

    (-0.353553 0.353553 0.6)

    (-0.353553 -0.353553 0.6)

    (0.353553 -0.353553 0.6)

);



blocks

(

    // center block 1

    hex (2 3 0 1 18 19 16 17) (23 23 53) simpleGrading (1 1 2.5)

    // right 1

    hex (3 11 8 0 19 23 20 16) (17 23 53) simpleGrading (1 1 2.5)

    // top 1

    hex (1 0 8 9 17 16 20 21) (23 17 53) simpleGrading (1 1 2.5)

    // left 1

    hex (10 2 1 9 22 18 17 21) (17 23 53) simpleGrading (1 1 2.5)

    // bottom 1

    hex (10 11 3 2 22 23 19 18) (23 17 53) simpleGrading (1 1 2.5)



    // center block 2

    hex (18 19 16 17 6 7 4 5) (23 23 53) simpleGrading (1 1 0.4)

    // right 2

    hex (19 23 20 16 7 15 12 4) (17 23 53) simpleGrading (1 1 0.4)

    // top 2

    hex (17 16 20 21 5 4 12 13) (23 17 53) simpleGrading (1 1 0.4)

    // left 2

    hex (22 18 17 21 14 6 5 13) (17 23 53) simpleGrading (1 1 0.4)

    // bottom 2

    hex (22 23 19 18 14 15 7 6) (23 17 53) simpleGrading (1 1 0.4)

);



edges

(

    arc 11 8 (0.5 0 0)

    arc 8 9 (0 0.5 0)

    arc 9 10 (-0.5 0 0)

    arc 10 11 (0 -0.5 0)

    arc 15 12 (0.5 0 1.2)

    arc 12 13 (0 0.5 1.2)

    arc 13 14 (-0.5 0 1.2)

    arc 14 15 (0 -0.5 1.2)

    arc 23 20 (0.5 0 0.6)

    arc 20 21 (0 0.5 0.6)

    arc 21 22 (-0.5 0 0.6)

    arc 22 23 (0 -0.5 0.6)

);



patches

(

    wall sideWalls

    (

        (11 23 20 8)

        (23 15 12 20)

        (8 20 21 9)

        (20 12 13 21)

        (9 10 22 21)

        (21 22 14 13)

        (10 11 23 22)

        (22 23 15 14)

    )



    wall bottomWall

    (

        (2 3 0 1)

        (3 11 8 0)

        (0 8 9 1)

        (2 1 9 10)

        (2 10 11 3)

    )



    wall topWall

    (

        (6 7 4 5)

        (7 15 12 4)

        (4 12 13 5)

        (6 5 13 14)

        (6 14 15 7)

    )



);



mergePatchPairs

(

);



// ************************************************************************* //

Thanks Anton.

I am trying to extend this to a mesh around an airfoil, and it's pretty hard (well, in principle it's simple, but it's so tedious work :-) ). You wouldn't happen to have a version for an airfoil which might be easier to extend? I'd like to make an automatic blockMeshDict generator for airfoil meshes (say, from a x,y,z airfoil-data file).

/Mads

Unfortunately that's all I have, I've never tried to mesh an airfoil. Slightly offtopic, but isn't the mesh you need C-type? Because it collapses at the thin side of the foil?

Wouldn't it be possible to have your airfoil data-file as STL, and then just make the mesh with snappyHexMesh?

Anton, you are absolutely right about the C-mesh, typically used. But my airfoil has a blunt trailing edge (it's truncated and sharp), and an o-mesh is probably best in such cases.

I have tried snappyHexMesh (I think this tool is great, and I am looking forward to it being improved even more) but it has trouble with capturing the sharp trailing edge AND having it making boundary layers never really worked out for me...