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[blockMesh] Mesing a polar cylinder in x-direction

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Old   April 4, 2024, 14:39
Default Mesing a polar cylinder in x-direction
  #1
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Marķa Rosales
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Good day community,

Please, can you give me a hand in the block definition. I want to elaborate a cylindrical geometry, radial directions in y & z, and length along x-axis. The grid that I want is polar so I wanted to reproduce 4 times a quarter of cylinder but I got stucked in the block definition:

Code:
scale               1;

cx 0.0;
cy 0.0;
cz 80.0;

height 3;

r 45;

h #calc "$height+$cx";

vz #calc "$cz+$r";
nvz #calc "$cz-$r";

vy #calc "$cy+$r";
nvy #calc "$cy-$r";

c1 #calc "$cz + ($r*cos(45.0))"; // cosine in first quadrant
s1 #calc "$cy + ($r*sin(45.0))"; // sine

c2 #calc "$cz + ($r*cos(135.0))"; // cosine in first quadrant
s2 #calc "$cy + ($r*sin(135.0))"; // sine

c3 #calc "$cz + ($r*cos(225.0))"; // cosine in first quadrant
s3 #calc "$cy + ($r*sin(225.0))"; // sine

c4 #calc "$cz + ($r*cos(315.0))"; // cosine in first quadrant
s4 #calc "$cy + ($r*sin(315.0))"; // sine

vertices
(

($cx $cy $nvz) //0
($h $cy $nvz) //1
($h $vy $cz) //2
($cx $vy $cz) //3
($cx $nvy $cz) //4
($h $nvy $cz) //5
($h $cy $vz) //6
($cz $cy $vz) //7

($cx $cy $cz) //8
($h $cy $cz) //9

);

blocks
(
    hex (8 4 0 8 9 5 1 9) (1 15 15) simpleGrading (1 1 1)
    hex (8 0 3 8 9 1 2 9) (1 15 15) simpleGrading (1 1 1)
    hex (8 3 7 8 9 2 6 9) (1 15 15) simpleGrading (1 1 1)
    hex (8 7 4 8 9 6 5 9) (1 15 15) simpleGrading (1 1 1)
);

edges
(

    arc 0 1 ($cx $s1 $c1)
    arc 1 2 ($cx $s2 $c2)
    arc 2 3 ($cx $s3 $c3)
    arc 3 0 ($cx $s4 $c4)
    
    arc 4 5 ($h $s1 $c1)
    arc 5 6 ($h $s2 $c2)
    arc 6 7 ($h $s3 $c3)
    arc 7 4 ($h $s4 $c4)
    
);
The error in terminal is:

Code:
Creating block edges
No non-planar block faces defined
Creating topology blocks
--> FOAM Warning : 
    From Foam::vector Foam::cellModel::centre(const labelList&, const Foam::UList<Foam::Vector<double> >&) const
    in file meshes/meshShapes/cellModel/cellModel.C at line 63
    zero or negative pyramid volume: -12487.5 for face 1
--> FOAM Warning : 
    From Foam::vector Foam::cellModel::centre(const labelList&, const Foam::UList<Foam::Vector<double> >&) const
    in file meshes/meshShapes/cellModel/cellModel.C at line 63
    zero or negative pyramid volume: -6243.75 for face 3
--> FOAM Warning : 
    From Foam::vector Foam::cellModel::centre(const labelList&, const Foam::UList<Foam::Vector<double> >&) const
    in file meshes/meshShapes/cellModel/cellModel.C at line 63
    zero or negative pyramid volume: -2868.75 for face 4
--> FOAM Warning : 
    From Foam::vector Foam::cellModel::centre(const labelList&, const Foam::UList<Foam::Vector<double> >&) const
    in file meshes/meshShapes/cellModel/cellModel.C at line 63
    zero or negative pyramid volume: -2868.75 for face 5


--> FOAM FATAL IO ERROR: (openfoam-2306)
Block hex (8 3 7 8 9 2 6 9) (1 15 15) grading (1(1) 1(1) 1(1)) has inward-pointing faces
    4(3 7 6 2) 4(8 9 6 7) 4(8 8 7 3) 4(9 2 6 9) 

file: system/blockMeshDict.blocks at line 68.

    From void Foam::blockDescriptor::check(const Foam::Istream&)
    in file blockDescriptor/blockDescriptor.C at line 147.

FOAM exiting
Any comments are welcome
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Old   April 5, 2024, 06:46
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  #2
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Matthias Renaud
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Hola Maria,


I see a few errors in your blockMeshDict file.


First I assume the cos and sin function to take angle in rad as inputs, you could also used sqrt(2) just as I did.


Second your vertex 7 in not defined correctly, it should be ($cx $cy $vz)
you wrote $cz instead.


And last all your edges are wrong, there should be no arc between vertices 0 and 1, 6 and 7, 4 and 5, 2 and 3. Below is my version of the blockMeshDict (it works):



Code:
scale 1;

cx 0.0;
cy 0.0;
cz 80.0;

height 3;

r 45;

h #calc "$height+$cx";

vz #calc "$cz+$r";
nvz #calc "$cz-$r";

vy #calc "$cy+$r";
nvy #calc "$cy-$r";

c1 #calc "$cz + ($r / sqrt(2.0))"; // cosine in first quadrant
s1 #calc "$cy + ($r / sqrt(2.0))"; // sine

c2 #calc "$cz - ($r / sqrt(2.0))"; // cosine in first quadrant
s2 #calc "$cy + ($r / sqrt(2.0))"; // sine

c3 #calc "$cz - ($r / sqrt(2.0))"; // cosine in first quadrant
s3 #calc "$cy - ($r / sqrt(2.0))"; // sine

c4 #calc "$cz + ($r / sqrt(2.0))"; // cosine in first quadrant
s4 #calc "$cy - ($r / sqrt(2.0))"; // sine

vertices
(
    ($cx $cy $nvz) //0
    ($h $cy $nvz) //1
    ($h $vy $cz) //2
    ($cx $vy $cz) //3
    ($cx $nvy $cz) //4
    ($h $nvy $cz) //5
    ($h $cy $vz) //6
    ($cx $cy $vz) //7

    ($cx $cy $cz) //8
    ($h $cy $cz) //9

);

blocks
(
    hex (8 4 0 8 9 5 1 9) (15 15 15) simpleGrading (1 1 1)
    hex (8 0 3 8 9 1 2 9) (15 15 15) simpleGrading (1 1 1)
    hex (8 3 7 8 9 2 6 9) (15 15 15) simpleGrading (1 1 1)
    hex (8 7 4 8 9 6 5 9) (15 15 15) simpleGrading (1 1 1)
);

edges
(

    arc 7 3 ($cx $s1 $c1)
    arc 6 2 ($h $s1 $c1)
    
    arc 3 0 ($cx $s2 $c2)
    arc 2 1 ($h $s2 $c2)
    
    arc 0 4 ($cx $s3 $c3) 
    arc 1 5 ($h $s3 $c3)
    
    arc 4 7 ($cx $s4 $c4)
    arc 5 6 ($h $s4 $c4)
    
);

Have a nice day,
Matthias
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Old   April 5, 2024, 10:38
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  #3
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Marķa Rosales
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MUCHAS GRACIAS Matthias,

The cylinder worked with your solution!

Here I share how the blockMesh would look like:
Code:


scale 1;

cx 0.0;
cy 0.0;
cz 80.0;

height 3;

r 45;

h #calc "$height+$cx";

vz #calc "$cz+$r";
nvz #calc "$cz-$r";

vy #calc "$cy+$r";
nvy #calc "$cy-$r";

c1 #calc "$cz + ($r / sqrt(2.0))"; // cosine in first quadrant
s1 #calc "$cy + ($r / sqrt(2.0))"; // sine

c2 #calc "$cz - ($r / sqrt(2.0))"; // cosine in first quadrant
s2 #calc "$cy + ($r / sqrt(2.0))"; // sine

c3 #calc "$cz - ($r / sqrt(2.0))"; // cosine in first quadrant
s3 #calc "$cy - ($r / sqrt(2.0))"; // sine

c4 #calc "$cz + ($r / sqrt(2.0))"; // cosine in first quadrant
s4 #calc "$cy - ($r / sqrt(2.0))"; // sine

vertices
(
    ($cx $cy $nvz) //0
    ($h $cy $nvz) //1
    ($h $vy $cz) //2
    ($cx $vy $cz) //3
    ($cx $nvy $cz) //4
    ($h $nvy $cz) //5
    ($h $cy $vz) //6
    ($cx $cy $vz) //7

    ($cx $cy $cz) //8
    ($h $cy $cz) //9

);

blocks
(
    hex (8 4 0 8 9 5 1 9) (15 15 1) simpleGrading (1 1 1)
    hex (8 0 3 8 9 1 2 9) (15 15 1) simpleGrading (1 1 1)
    hex (8 3 7 8 9 2 6 9) (15 15 1) simpleGrading (1 1 1)
    hex (8 7 4 8 9 6 5 9) (15 15 1) simpleGrading (1 1 1)
);

edges
(

    arc 7 3 ($cx $s1 $c1)
    arc 6 2 ($h $s1 $c1)

    arc 3 0 ($cx $s2 $c2)
    arc 2 1 ($h $s2 $c2)

    arc 0 4 ($cx $s3 $c3)
    arc 1 5 ($h $s3 $c3)

    arc 4 7 ($cx $s4 $c4)
    arc 5 6 ($h $s4 $c4)

);

boundary
(
    upwind
    {
        type patch;
        faces
        (
    (8 0 4 8)
    (8 3 0 8)
    (8 7 3 8)
    (8 4 7 8)
            
        );
    }
    sides
    {
        type patch;
        faces
        (
    (0 4 5 1)
    (7 6 2 3)
    (5 6 7 4)
    (3 2 1 0)
        );
    }
    leeward
    {
        type patch;
        faces
        (
    (9 6 5 9)
    (9 5 1 9)
    (9 1 2 9)
    (9 2 6 9)
        );
    }
    
);

mergePatchPairs
(
);
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