[Nigel]

Hello, I am a student who is new to CFD in general. I wish to create a 'wind tunnel' kind of set-up on OpenFOAM and observe the flows around simple shapes. When I ran the blockMesh command, an error is returned. I would appreciate of anyone could help me take a look at the blockMeshDict that I have here and advise me if there is any easier alternatives to consider using for my other simulations.

This is basically a 2D simulation of a 1x1 unit square in a 5x5 unit 'wind tunnel'. I have 4 blocks of meshes (basically I'm not sure how to do it otherwise). An illustration is attached in the next post.

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  plus                                  |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

scale   1;

vertices
(
    (0 0 0)
    (5 0 0)
    (5 5 0)
    (0 5 0)
	
    (2 2 0)
    (3 2 0)
    (3 3 0)
    (2 3 0)
	
    (2 0 0)
    (3 0 0)
    (3 5 0)
    (2 5 0)

    (0 0 0.5)
    (5 0 0.5)
    (5 5 0.5)
    (0 5 0.5)
	
	(2 2 0.5)
	(3 2 0.5)
	(3 3 0.5)
	(2 3 0.5)
	
	(2 0 0.5)
	(3 0 0.5)
	(3 5 0.5)
	(2 5 0.5)	

);

blocks
(
        hex (3 0 8 11 15 12 20 23) (10 10 1) simpleGrading (1 1 1)
	hex (4 8 9 5 16 20 21 17) (10 10 1) simpleGrading (1 1 1)
	hex (2 10 9 1 14 22 21 13) (10 10 1) simpleGrading (1 1 1)
	hex (10 11 7 6 22 23 19 18) (10 10 1) simpleGrading (1 1 1)
);

edges
(
);

boundary
(

    fixedWalls
    {
        type wall;
        faces
        (
			(3 15 23 11)
			(11 23 22 10)
			(10 22 14 2)
			
			(12 0 8 20)
			(20 8 9 21)
			(21 9 1 13)
			
			(19 7 6 18)
			(4 16 17 5)
			(19 16 4 7)
			(6 5 17 18)

        );
    }

	
	inlet
    {
        type patch;
        faces
        (
            (3 0 12 15)
        );
    }
	
	outlet
    {
        type patch;
        faces
        (
            (14 13 1 2)
        );
    }
    frontAndBack
    {
        type empty;
        faces
        (
                        (16 17 18 19)
			(15 12 20 16 19 23)
			(16 20 21 17)
			(22 18 17 21 13 14)
			(23 19 18 22)
			
			(0 3 11 7 4 8)
			(9 8 4 5)
			(5 4 7 6)
			(6 7 11 10)
			(9 5 6 10 2 1)

        );
    }

);

mergePatchPairs
(
);

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

[Nigel]

CFD_Illustration.jpg

For illustration, I have attached how the block looks like. The area in the middle is the square to be placed in the 'wind tunnel'.

[clapointe]

To make the blockMeshDict easier, I think an easy way to make the mesh is to first create the 2d mesh. Then use topoSet to select a square of cells and subsetMesh to remove the cells. There are various tutorials that use subsetMesh -- eg : https://github.com/OpenFOAM/OpenFOAM...oscillatingBox.

Caelan

[simrego]

Hi!


If you have an error message then post it! It can help a LOT!
This kind of blocking i think can be done only with mergePatchPairs, or the adjacent block faces must be identical, so you will need 9 blocks for it (OFC if this square is a hole in the middle then only 8).

[yambanshee]

you have an inconsistant amount of cells between the upstream block and the top and bottom block as well as the downstream block and the top and bottom block. The way to do this is to create 8 different blocks; 4 corner blocks, one in front of the square, one behind the square and one on top and bottom of the square each.



Else you must make use of mergePatchPairs which may result in a messy solution, or you must take very careful care in setting up how many cells are in each block. The latter will become exceptionally difficult if you start using gradings, and is not recommended.