Remeshing in CFX using workbench meshing.
 

Cheers,

Some long time ago I posted a tutorial regarding remehsing in CFX using ICEM CFD as meshing tool. It resulted in a lot of questions which i appreciate.

We recently posted a new way of doing remeshing in CFX. This time it uses some scripting in workbench and launches the remesh in ANSYS Meshing.

This is very useful since the implementation towards ICEM today have some limitations.

The workbench remesh tutorial can be found on:

http://www.edr.no/blogg/ansys_blogge...nch_cfx_remesh


Klas Johansson, Ph.D.
Technical Consultant

EDR | Engineering Data Resources AB |
+46 31 759 5035 (tel) | +46 (0)708 87 92 72 (mobile)
mailto:klas.johansson@edr.se

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Nice one - good video, I will have to try it out some time.

You like doing things the hard way don't you? I would have been lazy and just used a rotating frame of reference :)

I've seen something similar from ANSYS, but it's nice to have a tutorial that anybody can access. One key point is that this approach is parameter driven, so if you have a body that bends for example (instead of behaving like a rigid body whose motion is easily described by parameters) then you still need to use the ICEM approach.

I like doing it the hard way. :) I was expecting that comment but it is just for demo purpose. Actually the hardest thing when creating an example is creating a case for the demo.

Correct me if im wrong but as the ICEM remesh approach is shipped with the ANSYS installation it only allows for translation in the three main coordinate directions. The ICEM implementation is also parameter driven since you do send values to describe the motion in between the programs.

I did some hacking of the script that handles the communicaiton some time ago to allow for rotational motion as well in ICEM but it was difficult to get it correct. The workbench approach allow for any motion out of the box as long as you can describe it with a parameter (e.g. translation, rotation, expansion ...).

If you have a thing that is bending in a controlled fashion think you would either run fluent that have remeshing in the solver (e.g. http://www.edr.no/blogg/ansys_blogge...n_ansys_fluent) or use keyframe swapping of the mesh. If you have something that is bending due to the flow (FSI) you are pretty stuck if the mesh-defomer cant handle the motion since we cant combine FSI and remshing in the current version. The main reason for this is that the mapping of the FSI load is today done at the start of a FSI simulation and if you do a remesh along the way the mapping is ruined.

Cheers
Klas

I thought there were two approaches with ICEM remeshing. One that was parameter driven and one that brought in the deformed mesh and created a faceted geometry. The latter would be suitable to general motion. I could be wrong since I haven't tried either of those.
Yes, with FSI you are basically stuck since you can't do re-meshing (without a lot of pain). Your best bet here is to try out the latest 14.0 preview release and use the new FLUENT 2-way FSI feature which allows remeshing.

Hi Klas,

Actually I'm pretty sure ANSYS has put remeshing for FSI cases as a beta feature for R13. I haven't tested it yet though, so I can't say if it works. If I have the time I'll try it and let you know.

Cheers

Would be nice with that second approach in ICEM but i havent seen any documentation for such a solution but i havent looked at it since version 12.1. The same goes for that beta feature. Sounds interesting if its true.

Im gonna look at this and come back with whats possible.

cheers

Looks like it is not doable with a facetted surface out of the box at least.


As indicated previously, only translational mesh motion is automatically handled by the ICEM CFD Replay remeshing option. This is accomplished by applying the displacements of centroids of boundaries in the ANSYS CFX analysis definition to parts in the ANSYS ICEM CFD geometry.

You're right, the ICEM re-meshing with a faceted geometry can't be done out of the box, it needs a bit of user scripting to work (according to the FSI training course material).
Re-meshing with FSI is definitely not a beta feature in R13. ANSYS simply says they don't support it, which I agree with given what's needed to get it to work.

Unfortunately, there seems to be some critical piece of information that is missing from the tutorial, because as it stands it does not actually work. Once the remeshing criteria is reached, the solver just remeshes over and over again, but the mesh is not actually replaced. I notice that the WB_Remesh.wbjn journal file is not included in the tutorial, so perhaps the one I created is somehow in error.

I've emailed the author and hopefully will get it cleared up soon.

You're right, I checked it and it apparently uses no special feature other then heavy manual work and scripting, plus setting almost everything (from the structural side) directly on ANSYS Classic.

I'm a CFD guy. Even though I have to use it from time to time, ANSYS Classic scares the hell out of me :)

Hello

I was trying to work through the tutorial but i do not know how to create the .wbjn file. I believe that is the "script" to actually create the mesh. Are there any tutorials for creating that or just any idea on how to do that.

The other question i have just deals with remeshing in V12.1 and V13. When i read up on V13 they talk about being able to stop, remesh and continue very easily and well. I assume the same goes for this tutorial. Is there a big difference in V13's ability to interpolate results when a new mesh is applied verses V12.1

Thank You,

DM

Wbjn. File
 

Hi

I am currently trying to simulate the erosion rate on a mixers rotor blades. I find your remesh method to be the perfect solution for my problem. Sadly I had no luck getting the .Wbjn File to work.
The solver usually starts its calculations till it gets to remesh, while doing so, the design modeller and the mesher open up for a brief moment. Following that the solver continues its calculations. Everything seems fine except that the results show no remeshing whatsoever.

I guess I can ask a question right off the bat: In order to create the correct .Wbjn File, when do I start recording and when do I quit recording?.

What I did so far, is start recording as soon as I started the program and stopped as soon as my mesh was green lighted by WB. I gotta also add that when I tried running the .Wbjn File to see if it replays my commands correctly, it created the geometry and the mesh, except that the mesh had much larger elements than the ones I chose.

I would appreciate every bit of help I can get

Remeshing in Workbench
 

The workbench remesh tutorial can be found on:

http://www.edr.no/blogg/ansys_blogge...nch_cfx_remesh


Hi Klas,
I am trying to remesh both way either by ICEM CFD or by workbench.During using ICEM I opened the replay ontrol window before importing the geometry from workbench and then I did the mesh and save as unstructured mesh usable in cfx and then save the replay file and close evrything. But when I used .tin and .rpl file in the cfx, the simulation ended with giving error(attached) just before starting the remesh. My remeshing condition was min orthogonality angle. I followed your(www.edr.no/bloog...) droping box tutorial using ICEM available in You Tube. My one is very similar, 'pipe penetration'. Can you/anyone please tell me what is the main reason. When should I open or close the replay window? Should anything more to do in replay control? or anything else?

On the other hand for using workbench I stuck in very earlier. How can I get the attached window(wndw 1) for input the parameter? I am using Ansys 13(academic). I can open 'mesh dialogue' and 'prameter set' seperately(as attached 'wndw 2') but how can I transfer/attached the parameter to the mesh? Please help me.

Thanks in advance!

for creating the parameter, open your geometry in Design Modeler and select your sketch, on the Details View window check the box on the left hand of desired Dimension.
you have to start recording your replay file after opening your geometry. you need to set up your meshing settings and create the mesh and then save your .rpl file

I have tried http://www.edr.no/blogg/ansys_blogge...nch_cfx_remesh
but I can not complete it. If someone can help me about inform more detail about that tutorial, please help me.
Thank you.

In the tutorial of discussion, the rotational angle (Rotangle) was sat as parameter, but I failed to understand which dimension is the Rotangle in the geometry of the tutorial?

How do I give rotational motion of rigid body in Design Modeller? I didn't find rotational angle in Dimensioning. Please help.

Hi adeban
So, can you prepare Script for rotational mesh motion with ICEM?
I can't find it yet! Can you help me?

Cheers

Hi Adeban,
Thanks for the share. I am currently trying to simulate the opening and closing of cantilever valve. Therefore, few gap (which local at the over-lip region between the cantilever and the base of the valve) will be variable from 0 (sealed) to some value (open). Is there a way to using the re-meshing function at that?
If yes, how can i do it?

Hi
I cant get the tutorials about remeshing. Would you please send me a link?
I dont know how to arrange ICEM in workbench. I dont know how to use beside CFX and Other Modules.

Hello,

I have the same problem as in the post above.
Does anybody have a working link to a tutorial for Ansys CFX remeshing?

Thank you

Here you go! Found in my archieve.

remesh script?
 

Hello,

I am doing a transient Valve opening calculation and:
Is it possible to get more information about the meshing script content in your tutorial? and how it was made?
is it possible to use cfx mesh-adaptation instead?

thanks,
Kazu

Hello there. Can you re-post all of your work again pls. Because all of the links are all dead already. I will very appreciate your work. Thank you!!!

Hi
This link doesn't work for me.
I was wondering if you could help me with that?
http://www.edr.no/blogg/ansys_blogge...nch_cfx_remesh