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Old   September 9, 2005, 16:07
Default MeshingSolidWorksModels(fluidBodiesAcisTranslated)
  #1
Mike Marcu
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Cogito et Communicando ergo Sum-To whoever can help,Thanks: I have a relatively large assembly-like a heat exchanger with many tubes ; The model is done in SolidWorks ;Then I use the cavity comand or fluid body command in Floworks to create the fluid body required by fluent. Then I save it in form of part then I save it in a translator like ACIS 8 or 14 or Parasolid or IGES or similar(there are cca 3-4 of them). Then I go to fluent and I import it -the best till now is ACIS14 (Parasolid failed to do the translation-I was surprised because the Solid Works has parasolid kernel). So I imported the model in Fluent and I started the Fluent mesher- but after cca 3 hrs the mesh failed. A colleague told me that he also did that but he had to work around the SW obtained model -to pick different elements and modify them etc. He told me that better to use the Fluent modeller . But in the case of a complex assembly like a large heat exchanger it is better if we can import it from Solid Works in the way I described above- Can anyone help to solve this dillema?
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Old   September 10, 2005, 10:41
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
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Amir
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you have to make sure there is no too small surface in your model before importing that to Gambit. Small surfaces somtimes appear in doing fillets and other modelling manipulations and make trouble for the mesh generator.

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Old   September 10, 2005, 21:34
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #3
Mike Marcu
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Reffering to Amir comment Thankls Amir, I wnat to ask a question- if I have a model done in SOlidWorks-like a heat exchanger- but of course simplified -generally I can trnaslate it immediately in Gambit using say the Acis translator? Then if this is appearing on the fluent screen, can I assume that will be meshed OK? or I have to check the geometry of this model that is to clean it to be meshed in Gambit? I do not understand why the meshing process failed after cca 3 hrs of trudging. Can we say that the mesher in Fluent even now with the new variants created (the Flowizard 2) is weak-difficult ?

What I have to so that a solid works model to be meshable in Fluent? what are the elementary rules to follow?

I'm able to create fluid bodies for fluent using the cavity command or the fluid body from Floworks-then it seems is not enough even the fluent model is obtained(via Acis translation). Is this a general problem? the general rule is that we have to use the fluent modeller all the time ? what we do when we have complex assemblies like a heat exchanger or something else?

Please help with more comment

Sincerely,

Mike Marcu
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Old   September 11, 2005, 11:27
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #4
Amir
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ok, I tell you my procedure for complex geometries

1. Do the modelling in Solidworks with paying attention to the fillets and other geometrical manipulations to not leave very small edges/faces as the consequence. By very small edges/faces I mean in the order of 1/5 (appx.) of the smallest mesh size that you have in mind

2. Export the Solidwords with ACIS ver 2.0. I found this version of SAT file more compatible with Gambit

3. Import the file to Gambit and start the mesh generation by "minimum edge length" option to have and idea about the minimum edge you have in your SAT file and where it is located. if it's needed to be joined to other faces, perform it and make the minimum edge length reasonable in size for mesh generation.

4. Perform the mesh generation starting from edges then surfaces and finally volume.

5. Import that to FLUENT and do an initial run to make sure it is not diverging.

6. Check out the results such as pressure and velocity contours to see if there's no odd distribution of that somewhere due to skewed and bad quality mesh

7. if it needs to be remeshed, go back to Gambit and fix the problem and if that doesn't help, do more simplification on your initial geometry in Solidworks

It's a tedious process but that's how you get a good result out of CFD!

Hope it helps

Amir

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Old   September 11, 2005, 12:01
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #5
Mike Marcu
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Dear Amir -Thank you Please tell me if you know in FloWizard the meshing procedure is the same as in the big Fluent? That is it is necessary to do the fluid body with cavity first then to import in fluent and then to mesh? or is a direct coommand like in Floworks?

I'll try the strategy tommorow morning

Thanks again

Mike
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Old   September 11, 2005, 19:00
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #6
Amir
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You're welcome, I am afraid that I can help you in FloWizard as I don't have any experience with that.

Good luck tomorrow

Amir

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Old   September 12, 2005, 14:23
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #7
Mike Marcu
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Thanks Amir We try to clarify ourselves to understand what we have to do I'll keep yourself posted what we did// I restart clearing the model and so on and implementing the Acis2 trsnalation.

Thank you for maintaining the spirit of the village alive. Sincerely,

Mike Marcu
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Old   September 13, 2005, 11:50
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #8
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Hello Mike,

Hope I can help you with this problem. Well, FloWizard as we speak is more of an Engineering tool and from your conversation I can guess that you are not a skilled CFD user.

You can import two type of models in FloWizard i,e your fluid volume or the actual solid geometry. In case of solid geometries floWizard creates the fluid volume for you by subtracting the geomtery from the fluid box it creates around it. Any ways, as far as the meshing is concerned, I would not use Flowizard's automatic meshing capability at all, I would rather import my own meshes into it and let it solve. The results should be fine and in case of flowizard 2 it uses the 6.3 solver which is better than the 6.1 series.

I hope this helped. Many thanks
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Old   September 14, 2005, 20:09
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #9
Mike Marcu
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Thank you for comments and help. The historic trend is to democratize the analysis automate the meshing process and the cleaning process to make them intelligent and to implement remote solving to do the applications in minutes That is the exercise to be a simple tool in a tool box and not necessarily a career-at that moment doesnt matter if you are or not a skilled CFD specialist.May be a semantic interface will make this even easier. I have a lot of hope for Flowizard ,Floworks and other sofwares which can help an ordinary designer to feedback and feedforward his concepts.
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Old   September 15, 2005, 12:28
Default Re: MeshingSolidWorksModels(fluidBodiesAcisTransla
  #10
Mike Marcu
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I have a strange question: Can I mesh the model in Cosmosworks or in Floworks then use it in Flowizard? (you suggested: "I would rather import my own meshes into it and let it solve") Now I remmeber that it is possible to translate via a mesh translator but this is all I remember.
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