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[Other] Issues replicating a mesh

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Old   June 27, 2018, 20:40
Default Issues replicating a mesh
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Hi all

I'm trying to replicate the results of this paper: https://www.sciencedirect.com/scienc...60132316300208

From the results section, discussing the second of the two meshes created, they state:

Quote:
The first mesh is 0.1 m above the underlying surface to fulfill the requirement of y*. The grid size in the vertical direction increases with a ratio of 1.05 until the grid is 50 m, and the grid remains 50 m from there to the top of the domain. The x-grid in and near the city region (−0.6 ≤ x/D ≤ 0.6) is set to 100 m to obtain detailed characteristics compared to the mesoscale model, and it is uniform. The x-grid far away from the city area (x/D> 1.4) is not as crucial, so the x-grid there is set to 500 m. Between these two regions, the x-grid increases from the city area to the direction outside the city with a ratio of 1.05, until the grid reaches 500 m.
I believe I have replciated the mesh faithfully using blockMesh:

Code:
/*--------------------------------*- 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;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 1000;

vertices
(

(0 0 0)//0
(6 0 0)//1
(14 0 0)//2
(55 0 0)//3
(0 0 0.98)//4
(6 0 0.98)//5
(14 0 0.98)//6
(55 0 0.98)//7
(0 0 2.98)//8
(6 0 2.98)//9
(14 0 2.98)//10
(55 0 2.98)//11

(0 1 0)//12
(6 1 0)//13
(14 1 0)//14
(55 1 0)//15
(0 1 0.98 )//16
(6 1 0.98 )//17
(14 1 0.98)//18
(55 1 0.98 )//19
(0 1 2.98)//20
(6 1 2.98)//21
(14 1 2.98)//22
(55 1 2.98)//23



	
);

blocks
(

    hex (0 1 13 12 4 5 17 16) (60 1 127) simpleGrading (1 1 500)
hex (1 2 14 13 5 6 18 17) (29 1 127) simpleGrading (5 1 500)
hex (2 3 15 14 6 7 19 18) (82 1 127) simpleGrading (1 1 500)

hex (4 5 17 16 8 9 21 20) (60 1 40) simpleGrading (1 1 1)
hex (5 6 18 17 9 10 22 21) (29 1 40) simpleGrading (5 1 1)
hex (6 7 19 18 10 11 23 22) (82 1 40) simpleGrading (1 1 1)




);

edges
(
);

boundary
(
    floor
    {
        type wall;
        faces
        (
		            (0 1 13 12)
					(1 2 14 13)
					(2 3 15 14)

        );
    }

    ceiling
    {
        type patch;
        faces
        (
		            (8 9 21 20)
					(9 10 22 21)
					(10 11 23 22)


        );
    }
    fixedWallsX1
    {
        type patch;
        faces
        (
            (0 12 16 4)
			(4 16 20 8)

        );
    }
	
	    fixedWallsX2
    {
        type patch;
        faces
        (

            (3 15 19 7)
			(7 19 23 11)

        );
    }
	

);

mergePatchPairs
(
);

// ************************************************************************* //
However, my results are fairly poor. When I set the bottom boundary as homogeneous heat transfer, the results across the left where the domain is more refined is vastly different to the other areas, and when I use checkMesh, I fail two mesh checks. Max aspect ratio is 5829, with number of cells 3486, and there are 8311 underdetermined cells.

The work I am trying to replicate was done in Fluent - is there some reason that OpenFOAM can't work with a mesh like this, or is this mesh in fact fine?
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