[Studentdrak]

Is there a way of deleting a 2d mesh region in cfx pre.

My model is too huge to remesh, if there is a way to delete 2d region in cfx pre it would be easier

pl. do reply asap

[ghorrocks]

You do not need to delete it. Just don't use it for anything and then it will not be included in the def file.

[Studentdrak]

Thanks ghorrocks,

But not using it, does not consider it as a default BC i.e., a wall in pre ?

[Studentdrak]

Thank u ghorrocks

I tried it, it is working. I had a perception that unused 2d regions will be considered as walls.

Thanks

[hosseinhgf]

could you please tell me how it's working?
unused faces appear in domain default and i cant delete or remove it. even when i turned off Automatic Default Domain and Automatic Default Interfaces.

[ghorrocks]

You delete the default domain and regenerate your own which only includes the ones you want - leave out the ones you do not want.

[Studentdrak]

hi hosseinhgf,
U will not be able to delete it. In my case, 2d regoin was already included in a user defined wall. So, there was no default domain default. I have just redefined the wall checking out the 2d region

[ghorrocks]

Yes, you can delete it. I have done it many times.

Also you can disable generation of the default domain so it starts with no domains defined so this might make things easier.

[hosseinhgf]

In “Multiphase Flow in a Mixing Vessel” tutorial when I use “MultiphaseMixer.pre” file in “Play Tutorial” just two face of blade defined as interface and the other faces not defined (used) in any boundary. But I cant do it manually. And if some faces weren’t in any boundary then are they “interior (interface)” faces?
I couldn’t delete these faces.
Imagine there is two cube that the smaller Is inside the bigger. Then you have bigger cube with 12 faces and the smaller cube with 6 faces. In pre you must define the faces between two cube; Wall or interface or anything you want but you can’t ignore it.

[hosseinhgf]

Ok I found what happened. These Faces (impeller faces that isn’t red in pic) automatically defined as interface that didn’t appear in pre but you can manually defined them. So you can’t delete these faces from “domain default” but you can ignore them because they automatically defined as interface (general connection, Conservative Interface Flux).

[Antech]

Hello.
I have also faced this problem with default interfaces...

I use Ansys 14.5 for this case (we have 16.2 installed but there are some problems with completing the calculation on a cluster). I disabled default interfaces in Pre and imported multi-body mesh generated in Meshing (Contacts checkbox in Open dialog is disabled). Nevertheless, when I create manual interface Pre colors it in red and doesn't write the solver input file because there are multiple BCs for the same regions. I showed 1:1 connections in "Connections" tree item, then I deleted all these connections. Nothing changed, although there are no any connections in tree-view now.

The problem is that case require many custom interfaces, not just "General connections", but it seems that automatically generated connections cannot be deleted via the Pre interface (or I don't know how to do it).

Connections appear in Pre because of mesh connections written by Ansys Meshing. I will now try to delete connections in Meshing (mesh is generated and these connections not required anymore), then save and import mesh in Pre.

Update
======
The problem was not solved. I deleted all contacts in Meshing, then saves the mesh and imported it into CFX Pre. It created 1:1 connections again. I deleted them but there are still errors of kind "one face belongs to various BCs" when writing solver input file.

Update-2
=======
I found the reason for this strange behavior. IMHO, it's a Meshing bug. In Geometry Modeler I see that my named selections has exactly one associated face. But when you group several bodies in part and then mesh with Ansys Meshing, the resulting mesh contains the same named selections with 2 faces! Second face is added by Meshing automatically if it contacts with first face (assigned in Geometry Modeler or Solid Works). It's obvious that using such "corrupted" named selections leads to incorrect BCs in CFX Pre.
I didnt find any easy method to cope with this bug. So now I delete incorrectly added faces from named selections in Pre manually, but serious disadvantage if this method is that CFX Pre is extremely slow on large meshes (current mesh contains around 150 millions of cells) and each named selection editing includes about 3 minutes of waiting for "Calculating geometry".