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Old   July 27, 2015, 00:38
Default Icem meshing queries
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Faizan
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Hi All,

I am new to ICEM meshing software. I have done available tutorials of ICEM 3D hexa-hedral meshing but I have few unclear queries.

I wish to develop 3D hexahedral blocking mesh on ICEM software. I have two fluid and two solid domains. The geometry comprised of one de-Laval nozzle (solid domain) carrying high pressure nitrogen gas (fluid domain) and impinging on titanium substrate (solid) placed in a cylindrical air domain (fluid). Now I am unclear how to use ICEM software for meshing.

Should I do meshing separately for all four geometries? or should I do meshing in an assembled form where all four geometries are correctly placed at their target locations? In case of separate meshing of four geometries, will there be an discontinuity in mesh elements or how mesh will be connected? In case of assembled meshing it is too complicated for so many surfaces and layers.

Any HELP form CFD and meshing experts will be highly appreciated.
Please help me in developing the mesh on ICEM.

Thanks in advance.
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Old   July 27, 2015, 22:48
Default Need Help from ICEM Experts. Please respond to my below query.
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Need Help from ICEM Experts. Please respond to my below query.
Quote:
Originally Posted by Mfaizan View Post
Hi All,

I am new to ICEM meshing software. I have done available tutorials of ICEM 3D hexa-hedral meshing but I have few unclear queries.

I wish to develop 3D hexahedral blocking mesh on ICEM software. I have two fluid and two solid domains. The geometry comprised of one de-Laval nozzle (solid domain) carrying high pressure nitrogen gas (fluid domain) and impinging on titanium substrate (solid) placed in a cylindrical air domain (fluid). Now I am unclear how to use ICEM software for meshing.

Should I do meshing separately for all four geometries? or should I do meshing in an assembled form where all four geometries are correctly placed at their target locations? In case of separate meshing of four geometries, will there be an discontinuity in mesh elements or how mesh will be connected? In case of assembled meshing it is too complicated for so many surfaces and layers.

Any HELP form CFD and meshing experts will be highly appreciated.
Please help me in developing the mesh on ICEM.

Thanks in advance.
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Old   July 28, 2015, 03:56
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Nikesh Bhattarai
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I think its better if you shared your question with a diagram/s so that readers can understand your problem easily.
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Old   July 28, 2015, 04:00
Default 3D Geometry attached
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3dGeom.jpg

Hi Nikesh,

I have attached a 3D geom explaining all four domains which i am interested in. Now please help me in developing an ICEM hexahedral mesh using blocking method.

Thanks

Faizan
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Old   July 28, 2015, 07:23
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Well, I did not exactly say that I would be the one to help you but I can only try, since I myself am new to ICEM and trying very hard to learn to mesh there.

Now coming back to your topic, I still cannot understand the physics of your problem. It seems like your problem is with the way to resolve the boundary or computational domain. Can you be more precise so that I can give it a try?

Regards,
Nikesh
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Old   July 28, 2015, 23:46
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Hi Nikesh- Actually my question is that as you see I have four geometries in my model so in ICEM what is the best method to create mesh of four geometries. Should I import all four geometries separately and develop mesh one by one separately or should I import all four in ICEM as an assembly and start creating a mesh. I need a simple technique to develop a mesh for these geometries. The physics is I am solving a supersonic gas flow. With nitrogen at high pressure and temperature in nozzle and exiting into air domain, Its a multicomponent flow.

Please suggest about it. Many Thanks in advance.

Cheers

faizan
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Old   July 29, 2015, 01:42
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You need to make one geometry, not assembly. Which software are you using to make ur CAD model? If you are using CATIA, there are two approaches:
1. Using "Generative Shape Design Tool" where you'll make only the surfaces of your model.
2. Using "part design" tool. Here you'll have to model the area/volume where fluid flows. The material of your solid is useless in CFD. You just treat them as "wall", which can just be a line or plane.
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Old   July 29, 2015, 01:59
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well I made geometry on ANSYS Design Modeler. I have imported in ICEM Meshing software. If I create mesh separately for all four geometries as you said then I have one query that when I call all four geom in ANSYS CFX, will there be a connectivity of nodes. For example the nodes of nozzle exit will have any connections with cylinderical surrounding domain as shown in my last posted pic. Please suggest me about it.

Many Thanks for your responses
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Old   July 29, 2015, 02:03
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Do you mean that one geometry should have all four domains. Is that what you mean by one geometry.

If I would do this then I would get so many curves, surfaces in ICEM software- means duplication and overlapping of surfaces and curves. How do you reckon nikesh?
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Old   July 29, 2015, 02:05
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So did you have any problem in importing the geometry in ICEM? How does your geometry look like in ICEM?
Can you share your geometry file and let me have a look?
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Old   July 29, 2015, 02:10
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Yes I have imported geometry in ICEM. It looks OK. But my question is that which way is better?

Like you said if I do import all geom as one file in ICEM would it be so confusing -I mean over lapping of same surfaces?

In your opinion, it is better to use all four geoms as one file in ICEM mesh software- Please confirm? If yes then I will do it and share it with you.

Regards

Faizan
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Old   July 29, 2015, 02:15
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Yes, one file should contain all your geometries.
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Old   July 29, 2015, 02:19
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Ok- Let me try this first. Thanks Nikesh
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Old   July 29, 2015, 02:36
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Hi Nikesh- Please check this out. I have called all three geometries in one in ICEM. IS It OK?

Now please suggest how should I start creating a mesh. Will Blocking method OK? Any tutorial or help will be appreciated alot.

Kindly reply,

Faizan
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Old   July 29, 2015, 02:39
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Hi Nikesh-

Please check this out. I have called all three geometries in one in ICEM. IS It OK? Is that you were suggesting me earlier.

3 Geoms Combine.jpg


Now please suggest how should I start creating a mesh. Will Blocking method OK? Any tutorial or help will be appreciated alot.

Kindly reply,

Faizan
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Old   July 29, 2015, 02:49
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Now I think you are ready to mesh.
Use this for your tutorial:
http://orange.engr.ucdavis.edu/ICEM1...al/itut110.pdf
Which version of Ansys are you using?

Most importantly, I would like to suggest you to think first what you want to measure or see or calculate using CFD in your case?

What is your inlet boundary condition? And what about Outlet?

Think of those points as well when you are doing it.
Good luck!
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Old   July 29, 2015, 02:56
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well I have idea about boundary conditions that nozzle inlet is my inlet boundary condition and I am using total pressure and total temperature for sure. the nozzle exit I have no boundary condition and the surrounding cylinder domain would be an Opening boundary condition for sure.

I want to measure few parameters like Velocity, Temperature at nozzle exit and within the air domain. Actually i would introduce titanium spherical particle to monitor the particle properties like velocity , temperature, pressure. I have experimental data and I am trying to simulate on ANSYS exactly meaning exact setup as in the lab.

It's a supersonic flow. My nightmare is that how would I handle so many nodes and curves. and I always have doubt that can I cut this geometry in ICEM software like can I chop it from center and can i see inside. Please suggest.

Many Thanks for your help.

Regards,

Faizan
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Old   July 29, 2015, 02:57
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I am using ANSYS 14.5.7. What version you are using at the moment?

Last edited by Mfaizan; July 29, 2015 at 02:58. Reason: typo
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Old   July 29, 2015, 03:22
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For the physics and nature of your flow you'll need help from you supervisor or experts in that field. I cannot really say much at the moment.
And ICEM is only for grid generation, and yes it does have options to let you see the inside once you mesh. I'm also using Ansys 14.5
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Old   July 30, 2015, 03:22
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Hi Nikesh,

I am working on icem mesh- I have one confusion about the material point and also with the block. As I showed you earlier that when I opened three geometries in ICEM- it showed three material points. Now when I created a block- by default it select the nozzle geom. Now I am confused that which block would be suitable. I have following questions:
1. Should I create the block inside the nozzle for gas domain.
2. When splitting the block should I split inside the nozzle.
3. Should I associate edges to the inside nozzle and gas domain curves.
4. Since I have cylindrical domain/geometries therefore the block is not exactly fitting because it is a square and my all three geometries are circular.

Please suggest. any help would be much appreciated.

Thanks in advance

Faizan
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