[snappyHexMesh] snappyHexMesh keeping internal geometry

ThibaudB · June 7, 2011, 05:53

Hi Everyone !

I am currently trying to run a conjugate heat transfer case based on building a Salome STL geometry, converting it to 2-D-compatible case using OpenFOAM through snappyHexMesh, and iterating this procedure with different STL geometries.

Everything worked well simulating as simpleFoam case, but at this point, I want to do a conjugate heat transfer case, which needs to keep the internal solid cylinder geometry.

Can snappyHexMesh be built so that it may not remove the geometry ? Or do somebody knows another solution to 're-include' this removed geometry easily in my case ? (basic hex mesh with few cells)

This question may sound a bit basic, but I've looked around and couldn't find any answers... any help would be greatly appreciated !

-Thibaud

niklas · June 7, 2011, 07:39

have you checked in the tutorial?
tutorials/mesh/snappyHexMesh/snappyMultiRegionHeater

asamit · September 4, 2011, 08:05

tutorials/mesh/snappyHexMesh/snappyMultiRegionHeater
is a case that assembling parts.
I would like to create partition so that the boundary faces and points are merged.
Is it possible?

ThibaudB · October 4, 2011, 07:33

@niklas

I did check it, and for some simple geometries (like cylinders), I could get the two separated regions, but more complicated shapes were leading to the creation of "domains" when splitting the mesh to regions, which were not compatible with the fluid/solid composition I wanted...

What are actually those "domains"?

@asamit

I have been using extrudeMesh functions to extract some specific regions for chtMultiRegion purposes, but it only helps for rather simple geometries... was that what you were meaning?

antonessiu · January 27, 2012, 09:20

hello ThibaudB

i have the same problem ! snappy/splitMesh generates not necessary domains*
have you found any solution?
Thanks
Antonello
PS: i have submit my case in other post but anybody help me !!!

ThibaudB · January 30, 2012, 05:24

Hello Antonello,

well, I found some ways to sove this problem, depending how complicated is the geometry.

First one was the use of a software to "extract" the faces out of my complex geometry (such bevel gears: http://www.elektrowerkzeuge-ersatzte...TE704za012.JPG)
something that sHM wasn't doing properly (thus generating a lot of those "domains"). This software is unfortunately not free, but solved this problem (check CastNet, from DHCAE-Tools).
On the other hand, a more simple designed geometry from those gears could be implemented without problems, only by identifying the different domains between solid and fluid area. Fact is that the toal number of domains should never exceed the amount of specified fluid/solid areas...

Does it give an answer to your question?

Regards,
Thibaud

antonessiu · January 30, 2012, 11:08

Dear ThibaudB,
Thank you so much for your help!
I prove CastNet ......
An other problem is the construction of stl file.
I generate a simple geometric shape (solid) with Salome, explode in faces and then exported the single surface in stl format.
When i collect the stl faces files in one file and run surfaceChek on this file one "error" occurred, the surface is disconnected.
Which is the procedure to create right surface closed stl file from singe stl surfaces (boundary) files ?
PS: is this possible with solid works?
Thank you so much again!

ThibaudB · January 31, 2012, 09:24

Hello Antonello,

I don't know about SolidWorks, I myself kept on using SalomeMeca for simple geometries, avoiding problems with sHM then.
Could you post your STL file, and also your Salome file as well?

Regards,
Thibaud

antonessiu · January 31, 2012, 10:27

hello ThibaudB,
i post my stl files:
1) pipe.zip contain the SALOME files and stl export from salome -> FLUIDO.stl and SOLIDO.stl
2) pipe_composed.zip contain single surface stl files of SOLIDO, FLUIDO and the "composition" of this files to form FLUIDO.stl and SOLIDO.stl
When i run surfaceChek on composed stl files (in pipe_composed.zip) SOLIDO.stl and FLUIDO.stl the surface is not closed.....

ebah6 · March 22, 2012, 16:59

Hello to everyone,

I run into a similar issue where the inner geometries were being deleted.
As far as being able to show the entire geometries, I figured out that one need to choose the location of locationInMesh point such that you can see all the geometries from it.
For example, if within your block (i.e., the one you create from blockMeshDict), say you have an open cylinder that contains other geometries, in such a case, one may consider placing the locationInMesh on the open side of the cylinder so that the inner geometries are not hidden from it by the outer cylinder.

I hope this will be helpful to some out there.
Also, It would great that one of the senior members say whether this analysis is correct.
Note I figured this out by going through the propeler tutorial in pimpleDyMFoam.

Best regards to all.

June 7, 2011, 05:53	snappyHexMesh keeping internal geometry	#1
ThibaudB New Member ThibaudB Join Date: Jun 2011 Posts: 5 Rep Power: 15	Hi Everyone ! I am currently trying to run a conjugate heat transfer case based on building a Salome STL geometry, converting it to 2-D-compatible case using OpenFOAM through snappyHexMesh, and iterating this procedure with different STL geometries. Everything worked well simulating as simpleFoam case, but at this point, I want to do a conjugate heat transfer case, which needs to keep the internal solid cylinder geometry. Can snappyHexMesh be built so that it may not remove the geometry ? Or do somebody knows another solution to 're-include' this removed geometry easily in my case ? (basic hex mesh with few cells) This question may sound a bit basic, but I've looked around and couldn't find any answers... any help would be greatly appreciated ! -Thibaud

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June 7, 2011, 07:39		#2
niklas Super Moderator Niklas Nordin Join Date: Mar 2009 Location: Stockholm, Sweden Posts: 693 Rep Power: 29	have you checked in the tutorial? tutorials/mesh/snappyHexMesh/snappyMultiRegionHeater

September 4, 2011, 08:05		#3
asamit New Member anonymous Join Date: Feb 2011 Posts: 22 Rep Power: 15	tutorials/mesh/snappyHexMesh/snappyMultiRegionHeater is a case that assembling parts. I would like to create partition so that the boundary faces and points are merged. Is it possible?

October 4, 2011, 07:33		#4
ThibaudB New Member ThibaudB Join Date: Jun 2011 Posts: 5 Rep Power: 15	@niklas I did check it, and for some simple geometries (like cylinders), I could get the two separated regions, but more complicated shapes were leading to the creation of "domains" when splitting the mesh to regions, which were not compatible with the fluid/solid composition I wanted... What are actually those "domains"? @asamit I have been using extrudeMesh functions to extract some specific regions for chtMultiRegion purposes, but it only helps for rather simple geometries... was that what you were meaning?

January 27, 2012, 09:20		#5
antonessiu New Member Antonello Join Date: Apr 2010 Posts: 20 Rep Power: 16	hello ThibaudB i have the same problem ! snappy/splitMesh generates not necessary domains* have you found any solution? Thanks Antonello PS: i have submit my case in other post but anybody help me !!!

January 30, 2012, 05:24		#6
ThibaudB New Member ThibaudB Join Date: Jun 2011 Posts: 5 Rep Power: 15	Hello Antonello, well, I found some ways to sove this problem, depending how complicated is the geometry. First one was the use of a software to "extract" the faces out of my complex geometry (such bevel gears: http://www.elektrowerkzeuge-ersatzte...TE704za012.JPG) something that sHM wasn't doing properly (thus generating a lot of those "domains"). This software is unfortunately not free, but solved this problem (check CastNet, from DHCAE-Tools). On the other hand, a more simple designed geometry from those gears could be implemented without problems, only by identifying the different domains between solid and fluid area. Fact is that the toal number of domains should never exceed the amount of specified fluid/solid areas... Does it give an answer to your question? Regards, Thibaud

January 30, 2012, 11:08		#7
antonessiu New Member Antonello Join Date: Apr 2010 Posts: 20 Rep Power: 16	Dear ThibaudB, Thank you so much for your help! I prove CastNet ...... An other problem is the construction of stl file. I generate a simple geometric shape (solid) with Salome, explode in faces and then exported the single surface in stl format. When i collect the stl faces files in one file and run surfaceChek on this file one "error" occurred, the surface is disconnected. Which is the procedure to create right surface closed stl file from singe stl surfaces (boundary) files ? PS: is this possible with solid works? Thank you so much again!

January 31, 2012, 09:24		#8
ThibaudB New Member ThibaudB Join Date: Jun 2011 Posts: 5 Rep Power: 15	Hello Antonello, I don't know about SolidWorks, I myself kept on using SalomeMeca for simple geometries, avoiding problems with sHM then. Could you post your STL file, and also your Salome file as well? Regards, Thibaud

March 22, 2012, 16:59		#10
ebah6 Member Elh. A2. BAH Join Date: Jan 2012 Posts: 64 Rep Power: 14	Hello to everyone, I run into a similar issue where the inner geometries were being deleted. As far as being able to show the entire geometries, I figured out that one need to choose the location of locationInMesh point such that you can see all the geometries from it. For example, if within your block (i.e., the one you create from blockMeshDict), say you have an open cylinder that contains other geometries, in such a case, one may consider placing the locationInMesh on the open side of the cylinder so that the inner geometries are not hidden from it by the outer cylinder. I hope this will be helpful to some out there. Also, It would great that one of the senior members say whether this analysis is correct. Note I figured this out by going through the propeler tutorial in pimpleDyMFoam. Best regards to all.