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How to increase Mesh near the surface of the model

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Old   September 1, 2008, 10:23
Default hi, i am use OF1.4,i don't kn
  #1
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weihong yao
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hi,
i am use OF1.4,i don't know how to increase Mesh near the surface of the model?
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Old   September 1, 2008, 12:19
Default If you talk about the surface
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Niels Gjoel Jacobsen
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If you talk about the surface of some multiphase flow, then I do not think it is straight forward.

If you talk about increasing the number of computational cells toward the boundaries of your computational domain, then look into the user guide, the meshing chapter and especially the grading routines.

- Niels
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Old   September 1, 2008, 21:16
Default hi, I think i have got your m
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hi,
I think i have got your message.thank you!
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Old   September 1, 2008, 22:20
Default hi, i have followed your sugg
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weihong yao
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hi,
i have followed your suggestion.but it can not increase nunber of the cells.my blockMesh.file are follow:
vertices
(
(-3 -3 0)
(3 -3 0)
(3 3 0)
(-3 3 0)
(-3 -3 6)
(3 -3 6)
(3 3 6)
(-3 3 6)
(-39 -3 0)
(-39 3 0)
(-39 -3 6)
(-39 3 6)
(153 -3 0)
(153 3 0)
(153 -3 6)
(153 3 6)
(-3 -60 0)
(3 -60 0)
(-3 -60 6)
(3 -60 6)
(-3 60 0)
(3 60 0)
(-3 60 6)
(3 60 6)
(-39 -60 0)
(153 -60 0)
(153 60 0)
(-39 60 0)
(-39 -60 6)
(153 -60 6)
(153 60 6)
(-39 60 6)
(-39 -60 60)
(153 -60 60)
(153 60 60)
(-39 60 60)
(-39 -3 60)
(-39 3 60)
(-3 -60 60)
(3 -60 60)
(153 -3 60)
(153 3 60)
(-3 60 60)
(3 60 60)
(-3 -3 60)
(3 -3 60)
(3 3 60)
(-3 3 60)
);

blocks
(
hex (24 16 0 8 28 18 4 10) (36 57 6) simpleGrading (1 1 1)
hex (28 18 4 10 32 38 44 36) (36 57 54) simpleGrading (1 1 1)
hex (16 17 1 0 18 19 5 4) (6 57 6) simpleGrading (1 1 1)
hex (18 19 5 4 38 39 45 44) (6 57 54) simpleGrading (1 1 1)
hex (17 25 12 1 19 29 14 5) (150 57 6) simpleGrading (1 1 1)
hex (19 29 14 5 39 33 40 45) (150 57 54) simpleGrading (1 1 1)
hex (1 12 13 2 5 14 15 6) (150 6 6) simpleGrading (1 1 1)
hex (5 14 15 6 45 40 41 46) (150 6 54) simpleGrading (1 1 1)
hex (2 13 26 21 6 15 30 23) (150 57 6) simpleGrading (1 1 1)
hex (6 15 30 23 46 41 34 43) (150 57 54) simpleGrading (1 1 1)
hex (3 2 21 20 7 6 23 22) (6 57 6) simpleGrading (1 1 1)
hex (7 6 23 22 47 46 43 42) (6 57 54) simpleGrading (1 1 1)
hex (9 3 20 27 11 7 22 31) (36 57 6) simpleGrading (1 1 1)
hex (11 7 22 31 37 47 42 35) (36 57 54) simpleGrading (1 1 1)
hex (8 0 3 9 10 4 7 11) (36 6 6) simpleGrading (1 1 1)
hex (10 4 7 11 36 44 47 37) (36 6 54) simpleGrading (1 1 1)
hex (4 5 6 7 44 45 46 47) (6 6 54) simpleGrading (1 1 1)
);

edges
(
);

patches
(
patch inlet
(
(27 9 11 31)
(37 11 31 35)
(9 8 10 11)
(11 10 36 37)
(8 24 28 10)
(10 28 32 36)
)
patch outlet
(
(25 12 14 29)
(29 14 40 33)
(12 13 15 14)
(14 15 41 40)
(13 26 30 15)
(15 30 34 41)
)
wall front
(
(0 3 7 4)
)
wall <back>
(
(1 2 6 5)
)
wall <left>
(
(0 1 5 4)
)
wall <right>
(
(2 3 7 6)
)
wall <top>
(
(4 5 6 7)
)
empty <wall>
(
(24 16 18 28)
(28 18 38 32)
(16 17 19 18)
(18 19 39 38)
(17 25 29 19)
(19 29 33 39)
(26 21 23 30)
(30 23 43 34)
(21 20 22 23)
(23 22 42 43)
(20 27 31 22)
(22 31 35 42)
(32 38 44 36)
(44 36 37 47)
(47 37 35 42)
(38 39 45 44)
(44 45 46 47)
(47 46 43 42)
(39 33 40 45)
(40 45 46 41)
(41 46 43 34)
(16 24 8 0)
(0 8 9 3)
(3 9 27 20)
(17 16 0 1)
(2 3 20 21)
(25 17 1 12)
(12 1 2 13)
(13 2 21 26)
)
wall <bottom>
(
)
);

mergePatchPairs
(
);
I change the simpleGrading(1 1 1) by (1 1 5).my geometry is very simple ,just put the 6*6*6 cube into 192*120*60 box.my purpose is increasing grid near the surface of the cube.
would someone help me?
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Old   September 1, 2008, 22:32
Default Hi, WeiHong, First of all,
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Hi, WeiHong,

First of all, changing simpleGrading, which is cell expansion ratios, will not increase the number of cells.
Read the manual here:
http://www.opencfd.co.uk/openfoam/do...#x25-1390005.3

Hmm.. I see what you try to do. Well, where do you put that (1 1 5)? If you really want to intensively increase the number of cells close to surface, I recommend you to add one more strip above.. It is not too hard, but tedious, somehow.

iL
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Old   September 1, 2008, 23:44
Default hi,ivan, thank you for giving
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hi,ivan,
thank you for giving the feedback! first, i put the (1 1 5)into simpleGrading of the blocks,as follow:
hex (24 16 0 8 28 18 4 10) (36 57 6) simpleGrading (1 1 5)
hex (28 18 4 10 32 38 44 36) (36 57 54) simpleGrading (1 1 5)
hex (16 17 1 0 18 19 5 4) (6 57 6) simpleGrading (1 1 5)
hex (18 19 5 4 38 39 45 44) (6 57 54) simpleGrading (1 1 5)
hex (17 25 12 1 19 29 14 5) (150 57 6) simpleGrading (1 1 5)
hex (19 29 14 5 39 33 40 45) (150 57 54) simpleGrading (1 1 5)
hex (1 12 13 2 5 14 15 6) (150 6 6) simpleGrading (1 1 5)
hex (5 14 15 6 45 40 41 46) (150 6 54) simpleGrading (1 1 5)
hex (2 13 26 21 6 15 30 23) (150 57 6) simpleGrading (1 1 5)
hex (6 15 30 23 46 41 34 43) (150 57 54) simpleGrading (1 1 5)
hex (3 2 21 20 7 6 23 22) (6 57 6) simpleGrading (1 1 5)
hex (7 6 23 22 47 46 43 42) (6 57 54) simpleGrading (1 1 5)
hex (9 3 20 27 11 7 22 31) (36 57 6) simpleGrading (1 1 5)
hex (11 7 22 31 37 47 42 35) (36 57 54) simpleGrading (1 1 5)
hex (8 0 3 9 10 4 7 11) (36 6 6) simpleGrading (1 1 5)
hex (10 4 7 11 36 44 47 37) (36 6 54) simpleGrading (1 1 5)
hex (4 5 6 7 44 45 46 47) (6 6 54) simpleGrading (1 1 5)
);
is that the only way to increase the grid close the surface of cube?you mean that create more vertices and blocks?
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Old   September 2, 2008, 13:10
Default hi, weihong, Yes, you can cre
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Ivan Lau
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hi, weihong,
Yes, you can create more vertices and blocks next to surface and increase the number of cells here. Does your blockMesh work? If so, what you did now is to put the bottom cells with closer space and the top cells far apart....
Did you follow the meshing routine like what Niels suggest? Read words by words on manual of Meshing. You can easily solve this problem.
Regards,
iL
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Old   September 3, 2008, 04:16
Default hi, thank you!i solved th
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hi,
thank you!i solved the problem. thank you!
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