[athnk]

Hello

Do you know if it is possible to create an overset mesh using ANSA?

[vangelis]

interesting question
For which solver if I may ask?

[athnk]

For Fluent. The overset mesh option has just been added recently.

[vangelis]

Indeed you are right about Fluent recently supporting this feature.

I have not tested it yet, but I believe that there should not be a problem to create
independent msh files from ANSA and then Fluent should handle the overset coupling.
Have you tried it and found a problem?

[athnk]

I haven't tried it yet, since I'm not familiar with this method in general.
I will try it soon, hopefully with no issues...

[vangelis]

Do let me know please!

[vangelis]

We actually tested it internally.
We output two overlaying unconnected volume meshes from ANSA in fluent msh format
We read it in Fluent
Changed the BC type of the outer surface of the inner volume to overset
Defined the overset interface
and the Fluent ran smoothly!

So no problem for ANSA

[athnk]

That is great!
Thank you so much for your immediate responses!

[vangelis]

you are welcome!

[athnk]

Hello again!

The past few days, I have been trying to run the overset mesh in Fluent.
Although it seems to work fine at first, with the setup of the boundary condition, Fluent insists on using my actual background mesh as the component mesh when setting up the interface and doesn't allow me to change that. I think it might be because there is a part of the component mesh that doesn't overlap, since when I used fully overlapping meshes everything was fine. Do you think there is some different way to merge the files before the input in Fluent to avoid this issue? Or is it a problem that occurs in Fluent and I can't do anything before?

[vangelis]

Hi there

Have you checked that you satisfy the condition mentioned in slide 5 in this presentation?
https://www.google.gr/url?sa=t&rct=j...r_Q4bzNqizsUOw

[athnk]

Well, I am not yet sure if the overset mesh is directly applicable to my geometry, since I also haven't seen any examples of it. My case is a rotating wheel on the ground, so it should have some points of overlapping boundaries but no intersections. I believe it satisfies those conditions, although I'm not sure about the 4 cell condition that is mentioned elsewhere. I just wanted to limit the origin of my problems to Fluent...

[vangelis]

So your model is a rotating tyre and its contact with the ground, and how for example water escapes?
Can you share an image of the model in ANSA?

[athnk]

For the time being I'm working on a very simple case and the point of using the overset mesh was supposed to be to simulate the wheel without the "base" that is normally used to have good quality elements around the contact patch.

[vangelis]

Could you try to use Volume>SET PID and assign the same PID
for the layers and the tetra mesh around the wheel?
Then you will only have two fluid zones and I believe it should be better for the overset condition

[athnk]

It works now! And the initial results look fine as well. There is a warning about orphan cells but I guess this was expected with the specific geometry.
Thank you very much again for your help!

[vangelis]

you are very welcome!