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[blockMesh] Blockmesh Spline usage strange simpleGrading behavior |
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June 9, 2023, 06:40
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Blockmesh Spline usage strange simpleGrading behavior
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#1 |
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New Member
Andrea
Join Date: Oct 2022
Posts: 3
Rep Power: 4  |
I am trying to make a "smart" mesh for a laminar flame, but I cant get why blockMesh is subdividing the blocks like that (look at the image I linked). I have tried both wiht simplegrading and edgegrading. The problem is on the blocks on the west side, near to the blocks boundaries the mesh goes from fine to course, but this is not specified. The only thing that works is not using any Spline/polyLine. If you have any suggestion/solution I would be happy to hear it.
Thanks in advance. Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 0.001;
vertices
(
(0 0 -15) // 0
(8 -0.13962634015954636 -30) // 1
(8 0.13962634015954636 -30) // 2
(0 0 15) // 3
(8 -0.13962634015954636 0) // 4
(8 0.13962634015954636 0) // 5
(45 -0.7853981633974483 0) // 6
(45 0.7853981633974483 0) // 7
(0 0 90) // 8
(8 -0.13962634015954636 75) // 9
(8 0.13962634015954636 75) // 10
(45 -0.7853981633974483 75) // 11
(45 0.7853981633974483 75) // 12
(8.5 0.14835298641951802 0) // 13
(8.5 -0.14835298641951802 75) // 14
(8.5 0.14835298641951802 75) // 15
(8.5 -0.14835298641951802 0) // 16
(0 0 17) // 17
(8 -0.13962634015954636 2) // 18
(8 0.13962634015954636 2) // 19
(8.5 -0.14835298641951802 2) // 20
(8.5 0.14835298641951802 2) // 21
(45 -0.7853981633974483 2) // 22
(45 0.7853981633974483 2) // 23
);
blocks
(
hex ( 0 1 2 0 3 4 5 3 ) (40 1 40) edgeGrading (1 1 1 1 1 1 1 1 1 1 1 1) //(0.7 1 0.15) //sw
hex ( 3 4 5 3 17 18 19 17 ) (40 1 33) edgeGrading (1 1 1 1 1 1 1 1 1 1 1 1) //(0.7 1 0.7) // cw
hex ( 17 18 19 17 8 9 10 8 ) (40 1 133) edgeGrading (1 1 1 1 1 1 1 1 1 1 1 1)//(0.7 1 22) // nw
hex ( 5 4 16 13 19 18 20 21 ) (1 30 33) simpleGrading (1 1 1)//(1 1 0.7) // cc
hex ( 19 18 20 21 10 9 14 15 ) (1 30 133) simpleGrading (1 1 1)//(1 1 22) // cn
hex ( 13 16 6 7 21 20 22 23 ) (1 40 33) simpleGrading (1 1 1)//(1 3 0.7) // ce
hex ( 21 20 22 23 15 14 11 12 ) (1 40 133) simpleGrading (1 1 1)//(1 3 22) // ne
);
boundary
(
inletFuel
{
type patch;
faces
(
(0 1 2 0)
);
}
wallOutside
{
type wall;
faces
(
(7 6 23 22)
(23 22 12 11)
);
}
wallTube
{
type wall;
faces
(
(2 1 5 4)
(5 4 16 13)
);
}
inletN
{
type patch;
faces
(
(13 16 6 7)
);
}
outlet
{
type patch;
faces
(
(8 9 10 8)
(10 9 14 15)
( 15 14 11 12 )
);
}
axis
{
type empty;
faces
(
(0 3 3 0)
(3 17 17 3)
(17 8 8 17)
);
}
frontAndBack_pos
{
type wedge;
faces
(
(0 2 3 5)
(3 5 17 19)
(17 19 8 10)
(5 13 19 21)
(19 21 10 15)
(13 7 21 23)
(21 23 15 12)
);
}
frontAndBack_neg
{
type wedge;
faces
(
(0 1 3 4)
(3 4 17 18)
(17 18 8 9)
(4 16 18 20)
(18 20 9 14)
(16 6 20 22)
(20 22 14 11)
);
}
);
edges
(
BSpline 17 19 ((0.2 0.003490658503988659 17) (1 0.017453292519943295 16.7) (7 0.12217304763960307 2.3) (7.8 0.1361356816555577 2))
BSpline 17 18 ((0.2 -0.003490658503988659 17) (1 -0.017453292519943295 16.7) (7 -0.12217304763960307 2.3) (7.8 -0.1361356816555577 2))
BSpline 3 4 ((0.2 -0.003490658503988659 15) (1 -0.017453292519943295 14.7) (7 -0.12217304763960307 0.3) (7.8 -0.1361356816555577 0))
BSpline 3 5 ((0.2 0.003490658503988659 15) (1 0.017453292519943295 14.7) (7 0.12217304763960307 0.3) (7.8 0.1361356816555577 0))
BSpline 0 1 ((0.2 -0.003490658503988659 -15) (1 -0.017453292519943295 -15.3) (7 -0.12217304763960307 -29.7) (7.8 -0.1361356816555577 -30))
BSpline 0 2 ((0.2 0.003490658503988659 -15) (1 0.017453292519943295 -15.3) (7 0.12217304763960307 -29.7) (7.8 0.1361356816555577 -30))
BSpline 8 9 ((0.2 -0.003490658503988659 90) (1 -0.017453292519943295 89.7) (7 -0.12217304763960307 75.3) (7.8 -0.1361356816555577 75))
BSpline 8 10 ((0.2 0.003490658503988659 90) (1 0.017453292519943295 89.7) (7 0.12217304763960307 75.3) (7.8 0.1361356816555577 75))
);
// ************************************************************************* //
Last edited by exnihilo; June 9, 2023 at 06:48. Reason: further explainations |
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June 10, 2023, 05:32
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#2 |
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Senior Member
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Hi exnihilo,
Thank you for sharing interesting problem. It looks like that positions given in spline edges prevents grading. I cannot suggest a direct solution unfortunately. To avoid the problem, we may use geometry and projection in blockMesh dict. With this method grading instruction works. I modified your dict as follows. Curves is obtained from spheres created in geometry sub-dict. Your can use arbitrary shape (stl files and others) instead of sphere. https://develop.openfoam.com/Develop.../blockMeshDict https://www.openfoam.com/documentati...-geometry.html Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// OpenFOAM v2212
scale 0.001;
// Geometric parameters
outerRadius 8;
geometry
{
sphere0
{
type sphere;
origin (0 0 -30);
radius $outerRadius;
}
sphere1
{
type sphere;
origin (0 0 0);
radius $outerRadius;
}
sphere2
{
type sphere;
origin (0 0 2);
radius $outerRadius;
}
sphere3
{
type sphere;
origin (0 0 75);
radius $outerRadius;
}
}
vertices
(
(0 0 -22) // -15) // 0
(8 -0.13962634015954636 -30) // 1
(8 0.13962634015954636 -30) // 2
//project (0 0 -15) (sphere) // 0
//project (8 -0.13962634015954636 -30) (sphere) // 1
//project (8 0.13962634015954636 -30) (sphere) // 2
(0 0 8) // 15) // 3
(8 -0.13962634015954636 0) // 4
(8 0.13962634015954636 0) // 5
(45 -0.7853981633974483 0) // 6
(45 0.7853981633974483 0) // 7
(0 0 83) // 90) // 8
(8 -0.13962634015954636 75) // 9
(8 0.13962634015954636 75) // 10
(45 -0.7853981633974483 75) // 11
(45 0.7853981633974483 75) // 12
(8.5 0.14835298641951802 0) // 13
(8.5 -0.14835298641951802 75) // 14
(8.5 0.14835298641951802 75) // 15
(8.5 -0.14835298641951802 0) // 16
(0 0 10) //17) // 17
(8 -0.13962634015954636 2) // 18
(8 0.13962634015954636 2) // 19
(8.5 -0.14835298641951802 2) // 20
(8.5 0.14835298641951802 2) // 21
(45 -0.7853981633974483 2) // 22
(45 0.7853981633974483 2) // 23
);
blocks
(
hex ( 0 1 2 0 3 4 5 3 ) (40 1 40) simpleGrading (0.25 1 1) // block 0 //(0.7 1 0.15) //sw
hex ( 3 4 5 3 17 18 19 17 ) (40 1 33) simpleGrading (0.25 1 1) //block 1 //(0.7 1 0.7) // cw
hex ( 17 18 19 17 8 9 10 8 ) (40 1 133) simpleGrading (0.25 1 1) // block 2 //(0.7 1 22) // nw
hex ( 5 4 16 13 19 18 20 21 ) (1 30 33) simpleGrading (1 1 1)//(1 1 0.7) // cc
hex ( 19 18 20 21 10 9 14 15 ) (1 30 133) simpleGrading (1 1 1)//(1 1 22) // cn
hex ( 13 16 6 7 21 20 22 23 ) (1 40 33) simpleGrading (1 1 1)//(1 3 0.7) // ce
hex ( 21 20 22 23 15 14 11 12 ) (1 40 133) simpleGrading (1 1 1)//(1 3 22) // ne
);
boundary
(
inletFuel
{
type patch;
faces
(
(0 1 2 0)
);
}
wallOutside
{
type wall;
faces
(
(7 6 23 22)
(23 22 12 11)
);
}
wallTube
{
type wall;
faces
(
(2 1 5 4)
(5 4 16 13)
);
}
inletN
{
type patch;
faces
(
(13 16 6 7)
);
}
outlet
{
type patch;
faces
(
(8 9 10 8)
(10 9 14 15)
( 15 14 11 12 )
);
}
axis
{
type empty;
faces
(
(0 3 3 0)
(3 17 17 3)
(17 8 8 17)
);
}
frontAndBack_pos
{
type wedge;
faces
(
(0 2 3 5)
(3 5 17 19)
(17 19 8 10)
(5 13 19 21)
(19 21 10 15)
(13 7 21 23)
(21 23 15 12)
);
}
frontAndBack_neg
{
type wedge;
faces
(
(0 1 3 4)
(3 4 17 18)
(17 18 8 9)
(4 16 18 20)
(18 20 9 14)
(16 6 20 22)
(20 22 14 11)
);
}
);
edges
(
//BSpline 17 19 ((0.2 0.003490658503988659 17) (1 0.017453292519943295 16.7) (7 0.12217304763960307 2.3) (7.8 0.1361356816555577 2))
//BSpline 17 18 ((0.2 -0.003490658503988659 17) (1 -0.017453292519943295 16.7) (7 -0.12217304763960307 2.3) (7.8 -0.1361356816555577 2))
project 17 19 (sphere2) // block 1-0 block 2-
project 17 18 (sphere2) // block 1-1 block 2-
//BSpline 3 4 ((0.2 -0.003490658503988659 15) (1 -0.017453292519943295 14.7) (7 -0.12217304763960307 0.3) (7.8 -0.1361356816555577 0))
//BSpline 3 5 ((0.2 0.003490658503988659 15) (1 0.017453292519943295 14.7) (7 0.12217304763960307 0.3) (7.8 0.1361356816555577 0))
project 3 4 (sphere1) // block 0-3
project 3 5 (sphere1) // block 0-2
/*
// BSpline
simpleSpline 0 1
(
(0.2 -0.003490658503988659 -15)
(1 -0.017453292519943295 -15.3)
(7 -0.12217304763960307 -29.7)
(7.8 -0.1361356816555577 -30)
)
//BSpline
simpleSpline 0 2 ((0.2 0.003490658503988659 -15) (1 0.017453292519943295 -15.3) (7 0.12217304763960307 -29.7) (7.8 0.1361356816555577 -30))
*/
project 0 1 (sphere0) // block 0-0
project 0 2 (sphere0) // block 0-1
//BSpline 8 9 ((0.2 -0.003490658503988659 90) (1 -0.017453292519943295 89.7) (7 -0.12217304763960307 75.3) (7.8 -0.1361356816555577 75))
//BSpline 8 10 ((0.2 0.003490658503988659 90) (1 0.017453292519943295 89.7) (7 0.12217304763960307 75.3) (7.8 0.1361356816555577 75))
project 8 9 (sphere3) // block 2-0
project 8 10 (sphere3) // block 2-1
);
// https://develop.openfoam.com/Development/openfoam/-/blob/master/tutorials/mesh/blockMesh/sphere7ProjectedEdges/system/blockMeshDict
faces
(
project (0 4) sphere0 // block 1: z-min
project (0 5) sphere1 // block 1: z-max
project (1 4) sphere1 // block 2: z-min
project (1 5) sphere2 // block 2: z-max
project (2 4) sphere2 // block ?: z-min
project (2 5) sphere3 // block ?: z-max
);
// ************************************************************************* //
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June 10, 2023, 05:42
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#3 |
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New Member
Andrea
Join Date: Oct 2022
Posts: 3
Rep Power: 4 |
Thank you very much! I thought spline was a good instrument since I could have made the flame on a super coarse mesh with a 1/2 step reaction mechanism and then I could have easily fitted the flame front on the spline. This would result in a super fine mesh where needed, but I think I can do something similar with a sphere, just fitting the sphere or with a generated .stl file. Thank you very much again for the suggestions, I will probably add this to the issues on openfoam site.
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| Tags |
| blockmesh, edgegrading, simplegrading |
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