[kane]

Hello All.

I'm a beginner on OpenFoam. I ran Sandia D flame tutorial and got results.

But values of results are too small.

So comparison between other result is very hard.

I want to scale up the mesh 4 times.

What should i do?

This is a blockMeshDict file.

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  5                                     |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
   (0     0                    -100)   // 0

   (3.6  -0.15717942211764708  -100)   // 1
   (3.6   0.15717942211764708  -100)   // 2

   (3.85 -0.168094659764705905 -100)   // 3
   (3.85  0.168094659764705905 -100)   // 4

   (9.1  -0.39731465035294123  -100)   // 5
   (9.1   0.39731465035294123  -100)   // 6

   (0     0                     0)     // 7

   (3.6  -0.15717942211764708   0)     // 8
   (3.6   0.15717942211764708   0)     // 9

   (3.85 -0.168094659764705905  0)     // 10
   (3.85  0.168094659764705905  0)     // 11

   (9.1  -0.39731465035294123   0)     // 12
   (9.1   0.39731465035294123   0)     // 13


   (150  -6.549142588235295     0)     // 14
   (150   6.549142588235295     0)     // 15

   (0     0                     500)   // 16

   (3.6  -0.15717942211764708   500)   // 17
   (3.6   0.15717942211764708   500)   // 18

   (3.85 -0.168094659764705905  500)   // 19
   (3.85  0.168094659764705905  500)   // 20

   (9.1  -0.39731465035294123   500)   // 21
   (9.1   0.39731465035294123   500)   // 22

   (150  -6.549142588235295     500)   // 23
   (150   6.549142588235295     500)   // 24
);

blocks
(
    hex ( 0  1  2  0  7  8  9  7)   (5  1 20)   simpleGrading (1 1 1)
    hex ( 3  5  6  4 10 12 13 11)   (5  1 20)   simpleGrading (1 1 1)

    hex ( 7  8  9  7 16 17 18 16)   (5  1 70)   simpleGrading (1 1 2)
    hex ( 8 10 11  9 17 19 20 18)   (1  1 70)   simpleGrading (1 1 2)
    hex (10 12 13 11 19 21 22 20)   (5  1 70)   simpleGrading (1 1 2)
    hex (12 14 15 13 21 23 24 22)   (60 1 70)   simpleGrading (3 1 2)
);

boundary
(
    inletCH4
    {
        type patch;
        faces
        (
            (1 0 0 2)
        );
    }

    wallOutside
    {
        type wall;
        faces
        (
            (14 15 24 23)
        );
    }

    wallTube
    {
        type wall;
        faces
        (
            (1 2 9 8)
            (10 11 9 8)
            (4 3 10 11)
            (5 6 13 12)
        );
    }

    inletPilot
    {
        type patch;
        faces
        (
            (5 3 4 6)
        );
    }

    inletAir
    {
        type patch;
        faces
        (
            (14 12 13 15)
        );
    }

    outlet
    {
        type patch;
        faces
        (
            (16 17 18 16)
            (17 19 20 18)
            (19 21 22 20)
            (21 22 24 23)
        );
    }

    axis
    {
        type empty;
        faces
        (
            (0 7 7 0)
            (7 16 16 7)
        );
    }

    frontAndBack_pos
    {
        type wedge;
        faces
        (
            (2 0 7 9)
            (6 4 11 13)

            (9 7 16 18)
            (11 9 18 20)
            (13 11 20 22)
            (15 13 22 24)
        );
    }

    frontAndBack_neg
    {
        type wedge;
        faces
        (
            (0 1 8 7)
            (3 5 12 10)

            (7 8 17 16)
            (8 10 19 17)
            (10 12 21 19)
            (12 14 23 21)
        );
    }
);

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

Any answers are okay!!

Best regards. Thank you

[aow]

If all you want to do is increase the dimensions by a factor of 4, then you probably only need to modify 2 things in the blockMeshDict file you posted.

First of all, multiply all of the coordinate values in the vertices section by 4. Secondly, you should increase the number of cells in the blocks section, perhaps by multiplying them by 4 too.

The blocks and boundary sections shouldn't need to change since all of the vertice numbers won't change.

Also, as a suggestion, could you not simply scale the results you already obtained up to a larger size using similitude concepts somehow? I'm not familiar with the application you're studying at all seeing as I'm a water/air multiphase problem guy so if my suggestion makes no sense, then ignore it.