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Propeller case diverges/stops by changing geometry

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Old   September 22, 2019, 10:59
Default Propeller case diverges/stops by changing geometry
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chandra shekhar pant
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Hello All,


I am trying to modify the propeller case by including my geometry/stl files into it. I created a hub+3 turbine (namely T1.stl) file and an inner cylinder (AMI.stl) file (which is a huge cylinder which includes these hub+3 turbine). Essentially two stl files, first is the combination of hub + 3 turbine and second is the AMI (arbitrary mesh interface).

Only 3 files I have changed (and all are attached herewith).
1. BlockMesh
2. SnappyHexMesh
3. CreatePatch (in which I removed all the patches except the AMI one, and changed from cyclicAMI to AMI only).


Particularly the simulation runs only for 10^-5 then shows the error:
GAMG: Solving for p, Initial residual = 5.24203e-49, Final residual = 5.24203e-49, No Iterations 0
time step continuity errors : sum local = 1.64601e-06, global = -3.20767e-14, cumulative = 7.38564
[1] #0 Foam::error:rintStack(Foam::Ostream&) at ??:?
[1] #1 Foam::sigFpe::sigHandler(int) at ??:?
[1] #2 ? in /lib/x86_64-linux-gnu/libc.so.6
[1] #3 Foam::symGaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) at ??:?
Any help or comment is highly welcomed. Thanks!
Attached Images
File Type: png mesh_rotor_ami.png (67.8 KB, 7 views)
Attached Files
File Type: c snappyHexMeshDict.c (2.6 KB, 0 views)
File Type: c createPatchDict.c (1.4 KB, 0 views)
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Old   September 22, 2019, 13:44
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Quote:
Originally Posted by chandra shekhar pant View Post
Hello All,


I am trying to modify the propeller case by including my geometry/stl files into it. I created a hub+3 turbine (namely T1.stl) file and an inner cylinder (AMI.stl) file (which is a huge cylinder which includes these hub+3 turbine). Essentially two stl files, first is the combination of hub + 3 turbine and second is the AMI (arbitrary mesh interface).

Only 3 files I have changed (and all are attached herewith).
1. BlockMesh
2. SnappyHexMesh
3. CreatePatch (in which I removed all the patches except the AMI one, and changed from cyclicAMI to AMI only).


Particularly the simulation runs only for 10^-5 then shows the error:
GAMG: Solving for p, Initial residual = 5.24203e-49, Final residual = 5.24203e-49, No Iterations 0
time step continuity errors : sum local = 1.64601e-06, global = -3.20767e-14, cumulative = 7.38564
[1] #0 Foam::error:rintStack(Foam::Ostream&) at ??:?
[1] #1 Foam::sigFpe::sigHandler(int) at ??:?
[1] #2 ? in /lib/x86_64-linux-gnu/libc.so.6
[1] #3 Foam::symGaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) at ??:?
Any help or comment is highly welcomed. Thanks!
Could you please share checkMesh metrics, and other settings as well?
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Old   September 23, 2019, 01:33
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chandra shekhar pant
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Dear HPE,



Many thanks for your prompt reply and sorry for the delayed response, actually its was night here and I was asleep. The Checkmesh.dat is attached herewith, I just noticed that it shows empty for AMI, not able to understand it, please find it herewith. Other settings are exactly the same as that of the tutorial. Nevertheless, if you require some particular, I will be happy to share with you.

Thanks again.
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File Type: c checkmesh.c (3.8 KB, 1 views)
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Old   September 23, 2019, 04:14
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Sorry for the incomplete checkMesh information. This is the complete information of the checkMesh, please ignore the previous one. Also in this I don't understand from where the innerCylinder_slave is coming, I haven't used it anywhere. Please have a look at the CheckMesh herewith.
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File Type: c checkMesh.c (4.5 KB, 2 views)
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Old   September 23, 2019, 07:34
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Could you please run:

checkMesh -allGeometry -allTopology

Could you also please attach:

constant/polyMesh/boundary ?
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Old   September 23, 2019, 07:44
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Sure, please find it herewith, since I thought that the innerCylinder_slave is being created inherently, therefore I put cyclicAMI for innerCylinder and innerCylinder_slave. Although not sure about this step but put it according to the tutorial.
Attached Files
File Type: c checkmesh_complete.c (9.1 KB, 4 views)
File Type: c boundary.c (1.9 KB, 3 views)
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Old   September 30, 2019, 08:24
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Any help? Also I found that that origin in dynamicMeshDict is playing a huge role in the stability of the simulations. My geometry has the center of mass at the origin but if I convert the *.stp file in *.stp file format the center of mass changes. I tried many software (like freeCAD, meshlab ) to make the center of mass of the *.stl file at the origin. Or rather tried to find out the center of mass of the stl file but nothing works. Is there any way to find the solution?

Many thanks!
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Old   October 1, 2019, 07:43
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Hi Chandra Shekar,

First of all you should improve your mesh. To be honest it is of poor quality. Have you improved your mesh?

Quote:
My geometry has the center of mass at the origin but if I convert the *.stp file in *.stp file format the center of mass changes.
If I understand properly, your gemetry have moved and if you view it in paraview it is not at the origin? If that is the case, extract the surface and transform the geometry using paraview filters.

If you are looking for editing softwares you have, Blender and Salome. Both are great in their own ways.

Cheers!
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Old   October 2, 2019, 02:11
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Hello Kmeti Rao,


Many thanks for your help and cooperation. I am not the expert of either of the softwares but had used the Salome and correct me if I am wrong:
I had created the stp file (the geometry) in freecad/salome and had fixed the center of mass at the Origin (0,0,0) using Salome. Then tried to import the stl file from the stp file in freecad (meshed it). I haven't meshed and imported in Salome because it was taking very long time and sometimes it was crashing. Now I have this stl file, which has been extracted by the stp file whose center of mass was (0,0,0) but after importing it to the stl files the center of mass changes and since Salome gives the center of mass only in geometry workbench. And consequently doesn't provide center of mass of the stl file. Hope I cleared my problem, if not yet, I will be happy to explain in depth.


Sincere thanks to you for helping me.
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