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-   -   meshing a cylinder (http://www.cfd-online.com/Forums/openfoam-meshing-blockmesh/86967-meshing-cylinder.html)

Nico A. April 7, 2011 11:09

meshing a cylinder
 
Hello at all,

my problem is the following: i want to simulate the flow around a cylinder. therefore i used the blockMeshDict of an openfoam tutorial ( /basic/potentialFoam/cylinder). i tried to create a full cylinder out of the existing mesh. this is what i tried for my blockMeshDict:

Quote:

vertices
(
(0.5 0 -0.5) //0
(1 0 -0.5) //1
(2 0 -0.5) //2
(2 0.707107 -0.5) //3
(0.707107 0.707107 -0.5) //4
(0.353553 0.353553 -0.5) //5
(2 2 -0.5) //6
(0.707107 2 -0.5) //7
(0 2 -0.5) //8
(0 1 -0.5) //9
(0 0.5 -0.5) //10
(-0.5 0 -0.5) //11
(-1 0 -0.5) //12
(-2 0 -0.5) //13
(-2 0.707107 -0.5) //14
(-0.707107 0.707107 -0.5) //15
(-0.353553 0.353553 -0.5) //16
(-2 2 -0.5) //17
(-0.707107 2 -0.5) //18
(0.5 0 0.5) //19
(1 0 0.5) //20
(2 0 0.5) //21
(2 0.707107 0.5) //22
(0.707107 0.707107 0.5) //23
(0.353553 0.353553 0.5) //24
(2 2 0.5) //25
(0.707107 2 0.5) //26
(0 2 0.5) //27
(0 1 0.5) //28
(0 0.5 0.5) //29
(-0.5 0 0.5) //30
(-1 0 0.5) //31
(-2 0 0.5) //32
(-2 0.707107 0.5) //33
(-0.707107 0.707107 0.5) //34
(-0.353553 0.353553 0.5) //35
(-2 2 0.5) //36
(-0.707107 2 0.5) //37
(2 -0.707107 -0.5) //38
(0.707107 -0.707107 -0.5) //39
(0.353553 -0.353553 -0.5) //40
(2 -2 -0.5) //41
(0.707107 -2 -0.5) //42
(0 -2 -0.5) //43
(0 -1 -0.5) //44
(0 -0.5 -0.5) //45
(-2 -0.707107 -0.5) //46
(-0.707107 -0.707107 -0.5) //47
(-0.353553 -0.353553 -0.5) //48
(-2 -2 -0.5) //49
(-0.707107 -2 -0.5) //50
(2 -0.707107 0.5) //51
(0.707107 -0.707107 0.5) //52
(0.353553 -0.353553 0.5) //53
(2 -2 0.5) //54
(0.707107 -2 0.5) //55
(0 -2 0.5) //56
(0 -1 0.5) //57
(0 -0.5 0.5) //58
(-2 -0.707107 0.5) //59
(-0.707107 -0.707107 0.5) //60
(-0.353553 -0.353553 0.5) //61
(-2 -2 0.5) //62
(-0.707107 -2 0.5) //63
);

blocks
(
hex (5 4 9 10 24 23 28 29) (10 10 1) simpleGrading (1 1 1)
hex (0 1 4 5 19 20 23 24) (10 10 1) simpleGrading (1 1 1)
hex (1 2 3 4 20 21 22 23) (20 10 1) simpleGrading (1 1 1)
hex (4 3 6 7 23 22 25 26) (20 20 1) simpleGrading (1 1 1)
hex (9 4 7 8 28 23 26 27) (10 20 1) simpleGrading (1 1 1)
hex (15 16 10 9 34 35 29 28) (10 10 1) simpleGrading (1 1 1)
hex (12 11 16 15 31 30 35 34) (10 10 1) simpleGrading (1 1 1)
hex (13 12 15 14 32 31 34 33) (20 10 1) simpleGrading (1 1 1)
hex (14 15 18 17 33 34 37 36) (20 20 1) simpleGrading (1 1 1)
hex (15 9 8 18 34 28 27 37) (10 20 1) simpleGrading (1 1 1)
hex (40 39 44 45 53 52 57 58) (10 10 1) simpleGrading (1 1 1)
hex (0 1 39 40 19 20 52 53) (10 10 1) simpleGrading (1 1 1)
hex (1 2 38 39 20 21 51 52) (20 10 1) simpleGrading (1 1 1)
hex (39 38 41 42 52 51 54 55) (20 20 1) simpleGrading (1 1 1)
hex (44 39 42 43 57 52 55 56) (10 20 1) simpleGrading (1 1 1)
hex (47 48 45 44 60 61 58 57) (10 10 1) simpleGrading (1 1 1)
hex (12 11 48 47 31 30 61 60) (10 10 1) simpleGrading (1 1 1)
hex (13 12 47 46 32 31 60 59) (20 10 1) simpleGrading (1 1 1)
hex (46 47 50 49 59 60 63 62) (20 20 1) simpleGrading (1 1 1)
hex (47 44 43 50 60 57 56 63) (10 20 1) simpleGrading (1 1 1)
);

edges
(
arc 0 5 (0.469846 0.17101 -0.5)
arc 5 10 (0.17101 0.469846 -0.5)
arc 1 4 (0.939693 0.34202 -0.5)
arc 4 9 (0.34202 0.939693 -0.5)
arc 19 24 (0.469846 0.17101 0.5)
arc 24 29 (0.17101 0.469846 0.5)
arc 20 23 (0.939693 0.34202 0.5)
arc 23 28 (0.34202 0.939693 0.5)
arc 11 16 (-0.469846 0.17101 -0.5)
arc 16 10 (-0.17101 0.469846 -0.5)
arc 12 15 (-0.939693 0.34202 -0.5)
arc 15 9 (-0.34202 0.939693 -0.5)
arc 30 35 (-0.469846 0.17101 0.5)
arc 35 29 (-0.17101 0.469846 0.5)
arc 31 34 (-0.939693 0.34202 0.5)
arc 34 28 (-0.34202 0.939693 0.5)
arc 0 40 (0.469846 -0.17101 -0.5)
arc 40 45 (0.17101 -0.469846 -0.5)
arc 1 39 (0.939693 -0.34202 -0.5)
arc 39 44 (0.34202 -0.939693 -0.5)
arc 19 53 (0.469846 -0.17101 0.5)
arc 53 58 (0.17101 -0.469846 0.5)
arc 20 52 (0.939693 -0.34202 0.5)
arc 52 57 (0.34202 -0.939693 0.5)
arc 11 48 (-0.469846 -0.17101 -0.5)
arc 48 45 (-0.17101 -0.469846 -0.5)
arc 12 47 (-0.939693 -0.34202 -0.5)
arc 47 44 (-0.34202 -0.939693 -0.5)
arc 30 61 (-0.469846 -0.17101 0.5)
arc 61 58 (-0.17101 -0.469846 0.5)
arc 31 60 (-0.939693 -0.34202 0.5)
arc 60 57 (-0.34202 -0.939693 0.5)
);

patches
(
symmetryPlane down
(
(42 43 56 55)
(41 42 55 54)
(43 50 63 56)
(50 49 62 63)
)
patch right
(
(2 3 22 21)
(3 6 25 22)
(2 38 51 21)
(38 41 54 51)
)
symmetryPlane up
(
(7 8 27 26)
(6 7 26 25)
(8 18 37 27)
(18 17 36 37)
)
patch left
(
(14 13 32 33)
(17 14 33 36)
(46 13 32 59)
(49 46 59 62)
)
symmetryPlane cylinder
(
(10 5 24 29)
(5 0 19 24)
(16 10 29 35)
(11 16 35 30)
(45 40 53 58)
(40 0 19 53)
(48 45 58 61)
(11 48 61 30)
)
);

mergePatchPairs
(
);

// ************************************************** *********************** //
when creating the block mesh topology, i get multiple warnings like:
Quote:

zero or negative pyramid volume: -0.0441942 for face 3
and
Quote:

From function blockMesh::createTopology(IOdictionary&)
in file createTopology.C at line 397
negative volume block : 10, probably defined inside-out
I dont know what it means and how to solve that problem.

with kind regards!


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