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meshing error when trying to sweep quad meshed faces in one domain
Posted May 12, 2011, 5:52 a.m. EDT Mesh Version 4.0a 7 Replies
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Hey All,
I have this pivot shell ,a cylinder with a thin diafragm along its inner surface (photo is attached if you are interested) and i need to manually mesh the geometry and bring the total number of elements to around 200.
the cylinder is 1.6 in long , 0.7 inch outter diameter and normal automatic meshing gives me around 8000 elements.
problem:
I take one end of the cylinder and one face of the diafragm and perform a quad surface mesh, then i try to sweep this surfaces through the entire geometry but i get errors all the time. seems like comsol can not handle sweeping through a geometry when quad surfaces' normal vectors are not aligned. Also, my geomtry is one unit and not an assmebly therefor i can not choose more than one surface as sweep target and since I initially had two or more source surfaces that just doesnt work.
please give me a hand here, im totally new to Comsol and I know what i know via meshing video tutorial on the website.
Notes:
I tried assembly before, inserted diafragm into the cylinder in Inventor, but upon import comsol had issues with tolerance and extra-small surfaces were introduced and it was a mess. so i went for a unity-like approach to help comsol get the hold of the thing easier!
Regards,
Ali
I have this pivot shell ,a cylinder with a thin diafragm along its inner surface (photo is attached if you are interested) and i need to manually mesh the geometry and bring the total number of elements to around 200.
the cylinder is 1.6 in long , 0.7 inch outter diameter and normal automatic meshing gives me around 8000 elements.
problem:
I take one end of the cylinder and one face of the diafragm and perform a quad surface mesh, then i try to sweep this surfaces through the entire geometry but i get errors all the time. seems like comsol can not handle sweeping through a geometry when quad surfaces' normal vectors are not aligned. Also, my geomtry is one unit and not an assmebly therefor i can not choose more than one surface as sweep target and since I initially had two or more source surfaces that just doesnt work.
please give me a hand here, im totally new to Comsol and I know what i know via meshing video tutorial on the website.
Notes:
I tried assembly before, inserted diafragm into the cylinder in Inventor, but upon import comsol had issues with tolerance and extra-small surfaces were introduced and it was a mess. so i went for a unity-like approach to help comsol get the hold of the thing easier!
Regards,
Ali
7 Replies Last Post May 16, 2011, 4:04 a.m. EDT
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Posted:
1 decade ago
Hi
you cannot sweep mesh such a geometry in one go, for that you need to "cut" it up in block elements, this can easily be done in most CAD software, but splicing the volume into several bodies, you should do that along the radial cylindrical direction (at least 2 times for r) and along the axis (at least in the middle)
for me the minimum would be to have the twoexternal half shell cylinders, the cylindrical body in two sections, and the internal cross bar body. This internal cross bar might have to be meshed in thets, in anycase I would mesh itas the last item on the list
By the way, you should patch your version to tha latest patch 3, see the main site.
--
Good luck
Ivar
you cannot sweep mesh such a geometry in one go, for that you need to "cut" it up in block elements, this can easily be done in most CAD software, but splicing the volume into several bodies, you should do that along the radial cylindrical direction (at least 2 times for r) and along the axis (at least in the middle)
for me the minimum would be to have the twoexternal half shell cylinders, the cylindrical body in two sections, and the internal cross bar body. This internal cross bar might have to be meshed in thets, in anycase I would mesh itas the last item on the list
By the way, you should patch your version to tha latest patch 3, see the main site.
--
Good luck
Ivar
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Posted:
1 decade ago
Thanks for the Advise Ivar,
Will give it a shot and update the issue. there still seems to be some misunderstanding tho.
I have "one" unit not an assembly, reason being that no matter how accurate I assemble the parts in CAD software (Inventor 11 in my case), comsol introduces gaps and steps on assembled interfaces.
again, i will import a simpler assembly and I will do as you suggested see how it goes.
Ali.
Will give it a shot and update the issue. there still seems to be some misunderstanding tho.
I have "one" unit not an assembly, reason being that no matter how accurate I assemble the parts in CAD software (Inventor 11 in my case), comsol introduces gaps and steps on assembled interfaces.
again, i will import a simpler assembly and I will do as you suggested see how it goes.
Ali.
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Posted:
1 decade ago
Hi
then I suspect that the data format of Inventor is not good enough, or the export options are not tuned to true "bodies"
--
Good luck
Ivar
then I suspect that the data format of Inventor is not good enough, or the export options are not tuned to true "bodies"
--
Good luck
Ivar
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Posted:
1 decade ago
...
I have "one" unit not an assembly, reason being that no matter how accurate I assemble the parts in CAD software (Inventor 11 in my case), comsol introduces gaps and steps on assembled interfaces.
...
Hi,
I have been struggling with Inventor 11 for the same reasong for a long time.
Please let me know whether you find any solution to this problem. I will let you know if I come up with anything good.
Cheers
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Posted:
1 decade ago
...been struggling with Inventor 11 for the same reasong for a long time.
Please let me know whether you find any solution to this problem....
So, I did manage to mesh my model and I dont really like how i did it ,or actually how comsol wants me to feed in the model, and here's how:
I took Ivar's advice and made seperate-common-shaped partitions out of it (One big tube ,two half washer-like elements and one simple slab,see attached ) and assembled them in my CAD software (inventor 11) and exported the assembly As it was. (NOT an IGS or STEP just as an assembly file (*.iam).
Upon import to Comsol make sure to choose these options (in 4.1 version):
- Geometry Representation/ CAD import Kernel
* this option requires the livelink for a CAD software license and It is a more powerful modeling kernel than the default kernel in Comsol so it can handle geometries better
-Form an Assembly(Although it is one Unit), otherwise you will get errors in meshing cause by interfaces
so taking these steps I can not mesh my design , I think this is a huge drawback of Comsol not being able to handle these geometries, At the end it all goes down to your geometry, change your assembly in a way that it is made of common shaped elements and you will get a way with it.
hope my experience helps you guys, ill be openning new threads asking new questions thats for Sure! :)
cheers
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Posted:
1 decade ago
Hi,
Thanks a lot for your reply. Unfortunately I cannot 'simplify' my geometry, I study and optimize devices in the fully turbulent flow regime and to modify the geometry so that is made of common shapes is not feasible, it would be more or less like asking Boeing to get rid of flaps from wings because they are too difficult to model at the boundary layer level ;-)
One more thing, you don't need the LiveLink, you just need the CAD import module to get the CAD import Kernel.
Thanks again.
Cheers
Thanks a lot for your reply. Unfortunately I cannot 'simplify' my geometry, I study and optimize devices in the fully turbulent flow regime and to modify the geometry so that is made of common shapes is not feasible, it would be more or less like asking Boeing to get rid of flaps from wings because they are too difficult to model at the boundary layer level ;-)
One more thing, you don't need the LiveLink, you just need the CAD import module to get the CAD import Kernel.
Thanks again.
Cheers
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Posted:
1 decade ago
Well I wish your problem was as simple as mine, but I guess at the end you just need to figure out a way to feed your problem in a way comsol can handle it part at the time.
Good Luck
Good Luck