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Meshing Approach?

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Old   December 5, 2017, 22:47
Default Meshing Approach?
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Erick
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I am having difficulty meshing the attached geometryConcentricTubeMultiphaseFlow-Unmeshed.jpg for a two phase mixing type application where I care about the volume fraction at various points along the tubes.
I have defined 3 bodies
Body 1 is the outer tube wall which carries the phase 1 material
Body 2 is the inner tube wall which carries the phase 2 material
Body 3 is the central cylinder of the inner wall that represents the initial volume of phase 2 material.
I assume velocity inlets for the phase 1 as the outer doughnut ring in the larger tube and phase 2 inlet as the central cylinder of the inner tube

(I have 3 bodies because I have been attempting boolean add/subtract techniques to build the phase 1 fluid body & the phase 2 fluid body)

I am having troubles meshing this structure. Specifically selecting lines, planes, or bodies for inflation layers to assign as the Inflation geometry and geometry boundary method/boundary. I would appreciate any suggestions and I will elaborate on any (unintended) omissions or ambiguities.

The mesh thus far will complete but has issues getting into the fluent solver... I'm guessing because of the multiple bodies defined and lack of definition of their interconnection.

Thanks in Advance!

Erick
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Old   December 6, 2017, 11:00
Default Additional thoughts
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Based on Peter023 here: FLUENT Periodic Boundary Condition SOLVED + TUTORIAL I suspect that my problem is tied to the fact that what I need to mesh is something of a union (using the nomenclature of the above inline image) between the void volume of the outer cylinder corresponding to the Phase 1 Velocity Inlet Boundary Plane and the volume of the Phase 2 Velocity Inlet Boundary Plane
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Old   December 6, 2017, 12:07
Question Virtual Bodies - Problem
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Based on https://www.sharcnet.ca/Software/Ans...al_bodies.html

It looks like defining a virtual body is the route I need to go given my fluid zones are voids in my existing cad models.

However - I now can't seem to enable this functionality

In the attached screen shot the Virtual Body button is disabled on the Geometry toolbar and when I right click Geometry in the Tree I do not get an option to create a virtual body.
I am using ANSYS 16.2
Virtual Body Creation Disabled.jpg
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Old   December 6, 2017, 18:39
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Micael Boulet
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I think what you need is only one fluid domain. You can get it with boolean operation.

Do you really need those 2 solid bodies (solid pipes)? I mean, do you intend to solve equations in the solid pipes, like heat conduction?
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Old   December 7, 2017, 13:35
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I do seem to need to do 2 fluid bodies and then join them at the outlet of the smaller tube because I can't seem to do an inflation layer on the inside of the smaller tube in addition to the inflation layers on the outer wall of the smaller tube and inside wall of the larger tube.

Yes I do eventually need the tube walls because the simulation will move to a 2 way FSI between the mixed fluid and the compliant tube walls.
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Old   December 7, 2017, 15:23
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how 2 bodies is going to help for inflation? What kind mesh are you trying to do?
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Old   December 7, 2017, 16:11
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I was able to do a subtraction boolean operation with a solid cylinder the size of ID of the outer tube and the inner tube model to create one solid fluid region that I was able to properly inflate around the inner tube inside & outside walls as well as the outer tubes ID surface. So from a meshing perspective I am ok for now - still need to get the outer tube model in at a later point in time for the 2 way FSI but I am able to get this into Fluent... now to troubleshoot all these errors:

Error at host: zone-surface: invalid thread[2]

Error at Node 0: zone-surface: invalid thread[2]

Error at Node 3: zone-surface: invalid thread[2]

Error at Node 4: zone-surface: invalid thread[2]

Error at Node 5: zone-surface: invalid thread[2]

Error at Node 7: zone-surface: invalid thread[2]

Error at Node 1: zone-surface: invalid thread[2]

Error at Node 6: zone-surface: invalid thread[2]

Error at Node 2: zone-surface: invalid thread[2]

Error: zone-surface: invalid thread[2]
Error Object: #f


after it finishes iterating on the first time step... Ugh! Any suggestions would be helpful
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Old   December 7, 2017, 16:17
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I saved everything and re-opened workbench from scratch then the solution:
When it opens up I get a whole slew of errors:
Preparing mesh for display...

Error at host: zone-surface: invalid thread[2]

Error at Node 0: zone-surface: invalid thread[2]

Error at Node 1: zone-surface: invalid thread[2]

Error at Node 2: zone-surface: invalid thread[2]

Error at Node 3: zone-surface: invalid thread[2]

Error at Node 4: zone-surface: invalid thread[2]

Error at Node 5: zone-surface: invalid thread[2]

Error at Node 6: zone-surface: invalid thread[2]

Error at Node 7: zone-surface: invalid thread[2]

Error: zone-surface: invalid thread[2]
Error Object: #f

Error at host: zone-surface: invalid thread[2]

Error at Node 0: zone-surface: invalid thread[2]

Error at Node 1: zone-surface: invalid thread[2]

Error at Node 2: zone-surface: invalid thread[2]

Error at Node 3: zone-surface: invalid thread[2]

Error at Node 4: zone-surface: invalid thread[2]

Error at Node 5: zone-surface: invalid thread[2]

Error at Node 6: zone-surface: invalid thread[2]

Error at Node 7: zone-surface: invalid thread[2]

Error: No journal response to dialog box message:'zone-surface: invalid thread[2]'
. Internally, cancelled the dialog.

Error: zone-surface: invalid thread[2]
Error Object: #f
Done.

Setting Post Processing and Surfaces information ... Done.

Interrupting...
Done.

Any thoughts on the nature of this error?
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