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Moving Mesh - General Evaluation

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Old   May 8, 2009, 11:17
Default Moving Mesh - General Evaluation
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Andy Robertson
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Folks,

First a caveat. I am ex-adapco and ran a fair number of moving mesh problems in my day. This includes funky things like sliding vane pumps, gear pumps as well as the more mundane moving-piston / moving-valve internal combustion engine problems.

My current employer uses FLUENT almost exclusively. However, I have a new program comming up which will require either
A. Purchasing extra Fluent Seats
B. Purchasing STAR-CD

The delta cost to my employer is essentially a wash.

I have played around with the sliding mesh capabiltiy a bit in FLUENT and it certainly works. But the animation / post processing available in FLUENT is certainly not up to what STAR-CD could do as of six years ago.

The documentation indicates that FLUENT can run the problems I have but.... I dont see any thing that would indicate it is any easier to use / set up that STAR-CD was. And I would certainly be ahead on the learning curve if I used STAR.

I dont seem to see a lot of in-cylinder questions from within the FLUENT community. Do many (or any) of you use FLUENT to do moving mesh on a regular basis?

What type of mesh motion? Sliding? Deforming? Layer addition / deleteion?

I am certainly leaning towards STAR-CD here but dont want to dismiss FLUENT out of hand.

Any input is appreciated.

Thanks
- Andy R
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Old   May 9, 2009, 03:17
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Maxime Perelli
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Quote:
Originally Posted by AndyR View Post
What type of mesh motion? Sliding? Deforming? Layer addition / deleteion?
*Sliding Mesh isn't a pure moving mesh, because it occures with interface, so the initial mesh remains the same, but it's just moved with an translation/rotation offset.
*Deforming Mesh (without interface) is used with Remeshing/Smoothing/Layering technics
-Remeshing-----> the solver will remesh the region according to the input parameters
-Smooting ------> the solver will stretch the region according to the input parameters
-Layering -------> the solver will add/suppress cell layers according to the input parameters

For in-cylinder problems, there is a special tool in Moving-Deforming Mesh.

Regarding the animation, I agree.... But there are workarounds
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Old   May 11, 2009, 11:28
Wink Moving Mesh
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Andy Robertson
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Max,
Thanks, but I dont think you quite understood the question. I am aware of Fluent's stated capabilities and the differences between them. What I am looking for is whether anyone out there is really using these on a daily basis on real geometries. All the commercial codes have a capabilities list that is found in thier brochures and manuals. The question is always whether these things really work as advertised. I feel the best judge of that is the end user. If 20 people responded over the next two weeks all saying "I use moving mesh feature XYZ at least once every NN months on problems of type IJK and am productive" I would feel confident in this tool for these problems.

Do you use these tools? How often? On what?

As to the animation work around... I have a philosphical objection to a $30,000 dollar (or more) piece of software which simply cannot do certain simple non-computational tasks with out "work-arounds". Animation is not a difficult problem, at least relative to the computational work itself. Animation has been part of FLUENT for over 10 years. At this point it should "just work".

I keep hoping that Dyson fellow will build a CFD code. I really love his vacuum cleaners

Thanks
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Old   May 11, 2009, 11:37
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I work with Layering feature without any problem.
Frequency: 2-4 times per year for moving piston in hydraulic devices
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