[Turbulence]

Hi Bruno

Thanks for the link. I tried various geometries and tried to vary the wall thickness and all, but found that the problem is geometry independent.
I resolved this problem by altering the grading of background mesh.
I made sure that the background mesh of big cylinder doesnot intersect my inlet pipe. Please look at the images attached.

Thank You everyone for your valuable suggestions
Turbulence.

[Turbulence]

Thank YOU

[hfs]

Originally Posted by wyldckat

Hi Turbulence,

I won't be able to look at this anytime soon... maybe this weekend. But in the meantime, I've picked up on this post:

The full link to where the tutorial is: http://www.openfoamworkshop.org/2012...enedeVilliers/

Best regards,
Bruno

Hello Bruno,

I am trying to get SHM snapping to my STL surface (see attachments). I have tried a lot and read a lot of solutions..
I have tried to play around with snapping parameters ... I increased snapping iterations (5000 iterations) ... I have disabled all snapping controls ... tried feature edge handling ... createBuffles command ... etc.

I have learn from this thread (handling of baffle regions or surfaces with zero thickness with snappyHexMesh)... and it improved a bit (see attached photo) .. but still poor snapping

Same message: Did not successfully snap mesh. Giving up...

It would be really nice if you took a look and give me your advice

Attached are Photo of STL, photo of the snapped mesh, and the triSurface folder.
from here you can download the case:
http://dl.dropbox.com/u/32336583/Case.zip

Really appreciate your guidance!

Kind Regards,

[hfs]

a little detail on how Umb patch is generated in my case

I got Umb patch from an STL file... this is what I did

1-Extracted the geometry from the STL and convert it to emesh using the command: surfaceFeatureExtract -includedAngle 150 -writeObj constant/triSurface/Umb.stl Umb

2-Duplicated edges in emesh (simply by copy-pasting) as recommended here (snappyHexMesh: Feature snapping of thin membrane edge)

3-Converted this emesh file to faceZones by adding faceZone Umb; cellZone Umb; cellZoneInside inside; to snappyHexMeshDict as follows:

refinementSurfaces
{
Umb
{
// Surface-wise min and max refinement level
level (2 2);
faceZone Umb;
cellZone Umb;
cellZoneInside inside;
}
}


4- After the SHM, I converted this faceZones into Patches using the command: createBaffles Umb '(Umb Umb)'


Thanks in advance for your advice

[hfs]

Originally Posted by hfs

Hello Bruno,

I am trying to get SHM snapping to my STL surface (see attachments). I have tried a lot and read a lot of solutions..
I have tried to play around with snapping parameters ... I increased snapping iterations (5000 iterations) ... I have disabled all snapping controls ... tried feature edge handling ... createBuffles command ... etc.

I have learn from this thread (handling of baffle regions or surfaces with zero thickness with snappyHexMesh)... and it improved a bit (see attached photo) .. but still poor snapping

Same message: Did not successfully snap mesh. Giving up...

It would be really nice if you took a look and give me your advice

Attached are Photo of STL, photo of the snapped mesh, and the triSurface folder.
from here you can download the case:
http://dl.dropbox.com/u/32336583/Case.zip

Really appreciate your guidance!

Kind Regards,

I got an answer here:
snapEdge - failure

Thanks Forum!

[holodeck10]

Hello!
I am having a problem with the snapping of nodes onto a cylinder surface when using snappyHexMesh. I tried all the hints in this threat, which do not help in my case. I further tried closed cylinders in a fully surrounding blockMesh, from which I cut the part I am interested in: Nothing works. I am really frustrated. can someone help me, please?

I attach the case including bash script, which​ should illustrate the method I am trying to apply. I further attach some mesh scenes:
- refined blockMesh with cylinder surface (stl file),
- the castellated mesh with cylinder surface and
- the snapped mesh with cylinder surface.
I tried to modify any of the parameters. So far it seems to me, that using explicit feature edge refinement does not help and regionwise refinement eitern. Further, increasing iterations in the snapControls section and decreasing tolerance does not improve the result eiter. I have no idea what to try. Any advice is highly appreciated!
Best regards
Stefan

[David*]

Hi Stefan,

try it again using feature edge refinement and check the .eMesh-File with paraview beforehands. Increase the level of feature refinement. I had a similar problem but fixed it with this. The main difference is that I use the edge of a closing area on top of the cylinder, not of the cylinder itself, maybe it's important.
I guess it's on purpose that feature edge is commented and the .eMesh is zipped in your uploaded files?

Regards,
David

[holodeck10]

Hi David,

thank you very much for your reply. I tried to follow your recommendations. First I must admit, that I could not load constant/trisurface/cylinder.emesh (not the packed and neither the unpacked one). At least I dont know, which filter to use. I could load cylinder_edgeMesh.obj, cylinder_openEdges.obj and cylinder_regionEdges.obj. I further extracted the coordinates from the eMesh file. All looks good to me (see 20121111_4cylinder.eMesh_points.png). The points lie on the edges and their number corresponds to the blockMesh resolution (see 20121111_4.png). I refined the blockMesh a little further. I think it is ok to be able to represent the geometry (it is actually a bit finer than in the flange case, mentioned previously in this threat).

The *.eMesh file has been gzipped because I set writeCompression compressed in the system/controlDict.

As recommended in several tutorials, I extended the cylinder length so that it pierces out of the blockMesh in order to improve the upper and lower edges. That's why, I don't have closing areas for the cylinder. Following your recommendation, I tried to use a cylinders which has been closed with new geometry at teh top and at the bottom. The grid looks a bit different there, but it does not solve the problem (I don't attach the figure).

:-(

Best regards
Stefan

[David*]

Hi Stefan,

you're right, the .eMesh cant be opened, but the .obj-Files should do as well to check whether the creation of the edges was successful.

I really don't know why it doesnt work for you, sorry. Last thing you could try is

I use the edge of a closing area on top of the cylinder, not of the cylinder itself

They should be identical, but you never know

Regards,
David

[holodeck10]

I found a solution, finally. Two things should be changed in my case:

1) The stl surface should surround the numerical domain instead of the cylinder to cut out.
2) Unfortunatelly, refineMesh cannot be applied in zones where it touches the stl file (see attached figure). This would lead to an error message.

I try to find a workaround for beeing still able to apply refineMesh in order to change the aspect ratio of cells, e.g. by generating a larger mesh and cutting the interesting part out afterwards.

Hope this is of use for you as well. Thanks to all who dedicated their time to my problem!

Cheers
Stefan