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Old   June 18, 2009, 23:10
Default What has happend to the edges of domain
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Hi,

I use rhoSimpleFoam to simulate a blade of gas turbine.

This is the picture of the simulation result.

http://user.qzone.qq.com/76247914/ph...FlyYK9YkAAA!!/

What has happend to the edges of domain?

Is there something wrong with the cyclic boundary conditions?
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Old   June 18, 2009, 23:13
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Old   June 18, 2009, 23:36
Default checkMesh
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checkMesh

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = constant

Time = constant

Mesh stats
points: 160248
faces: 454912
internal faces: 429824
cells: 147456
boundary patches: 6
point zones: 0
face zones: 0
cell zones: 0

Number of cells of each type:
hexahedra: 147456
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces ...
Patch Faces Points Surface topology
row_1_BLADE 6912 7128 ok (non-closed singly connected)
row_1_SHROUD 4608 4856 ok (non-closed singly connected)
row_1_HUB 4608 4856 ok (non-closed singly connected)
row_1_OUTFLOW 1536 1617 ok (non-closed singly connected)
row_1_INFLOW 768 825 ok (non-closed singly connected)
row_1_PER 6656 6930 ok (non-closed singly connected)

Checking geometry...
This is a 3-D mesh
Overall domain bounding box (0.6063716664 -0.09400876493 -0.06) (0.8094251252 0.05889179552 0.163938279)
Mesh (non-empty) directions (1 1 1)
Mesh (non-empty, non-wedge) dimensions 3
Boundary openness (-2.53523191331e-19 3.19783473277e-19 4.97898165194e-19) Threshold = 1e-06 OK.
Max cell openness = 1.90379145707e-15 OK.
Max aspect ratio = 335.077993397 OK.
Minumum face area = 8.94726575451e-10. Maximum face area = 9.81471952282e-05. Face area magnitudes OK.
Min volume = 5.60997898251e-14. Max volume = 2.49818970804e-07. Total volume = 0.00251046768668. Cell volumes OK.
Mesh non-orthogonality Max: 50.1995248971 average: 14.3396737008 Threshold = 70
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 1.5808312121 OK.

Mesh OK.

End
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Old   June 19, 2009, 03:28
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Sorry, I can't see any pictures of your domain ...
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Old   June 19, 2009, 04:15
Default This is the picture
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This is the picture
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File Type: jpg ss1.JPG (59.1 KB, 30 views)
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Old   June 19, 2009, 04:34
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Yes this looks strange. Can you provide a picture of the actual mesh?
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Old   June 19, 2009, 04:43
Default this is grid
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this is grid
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File Type: jpg 11.jpg (55.7 KB, 15 views)
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Old   June 19, 2009, 04:47
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this is shroud grid
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File Type: png 33.png (29.0 KB, 13 views)
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Old   June 19, 2009, 04:59
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From my experience with interFoam I can tell that sometimes slightly skewed hex cells give rise to problems with the pressure.

This may be an explanation for the pressure field in proximity of the bend.

Using corrected schemes for snGrad solved the problem within interFoam.
Maybe you even have to increase the value of nonOrthogonalCorrectors, which triggers the number of correction loops within the solution of the momentum equation.

But this is not explaining the pressure region at the outlet.
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Old   June 19, 2009, 07:19
Default decoupling problem
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Is this decoupling problem?
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File Type: jpg 1111113.jpg (34.9 KB, 12 views)
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Old   June 19, 2009, 07:47
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Quote:
Originally Posted by yijin_li View Post
Is this decoupling problem?
I don't understand your question. What do you mean with 'decoupling problem'?

And what happend to your domain in the first picture?
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Old   June 19, 2009, 08:31
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Quote:
Originally Posted by sega View Post
I don't understand your question. What do you mean with 'decoupling problem'?

And what happend to your domain in the first picture?

I changed relTol from 0 to 0.05 in fvSolution, than the first picture is the result.

I found that there are some fluctuating of pressure near the outlet boundary.
I think that something wrong with pressure and velocity.
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