Contact surface generated betwwen surfaces not in contact
 

Hello

I am planning to do a conjugate heat transfer problem with a lot of spheres in a box. As in figure one the spheres arent in contact while the inerfaces shows a contact region for it..This goes away when I make sphere small and none of the spheres are close.

At present distance b/w two sphere is .005cm.

Could some one comment on this?

(Geometry creation and meshing in workbench)

delete all the contact regions listed!
use named selection for any contacts!

Indeed this is bit difficult to handle. But I can think of two ways to fix this.
1. Right click on the 'contacts' and select 'Repair Overlapping Contact Regions'. This should help eliminate or highlight the faces that appear in more than one interfaces. The operation will also generate an extra set of interfaces, you can check them and decide if you want to keep or delete them.

Another way is rather manual.
(1) Rename the solid spheres as sphere1, sphere2.... and so on.
(2) Delete all the interfaces.
(3) Generate automatic contact regions.
(4) Right click on 'Contacts' and you will see option for naming the interfaces according to body names. This will name the interfaces accordingly e.g. Bonded-fluid_To_Sphere1, Bonded-Sphere1_To_Sphere2 and so on.
Now you can clearly see which intefaces and between fluids and which ones are between spheres.

Are you using Design modeler or SpaceClaim for CAD? If you are using spaceclaim, then there is another way to do this.

Design modeler

I have no experience with DM. You can try those two tricks and let us know how it went.

the repair worked for me

I've faced with the same problem. The pipes of my heat exchanger aren't in contact, but contacts have been created.
I don't quite understand how you repared it.
Can you, please, tell, how you've solved it? You just manually deleted them?
My model includes only internal volume (i.e water, without metal cladding). So no regions should be created.
Is there any way how avoid the automatically creating these contacts? Or I just have to delete them?

The Ansys Workbench default is to automatically create contacts according to the default settings (whether or not you have a fluid or solid modeled is relevant to the contact creation tool).

You can change the default settings such that this doesn't happen in the future. For now, delete the auto-created contacts and then disable the creation of auto-contact generation selecting 'Connections' and disabling the 'auto-create on re-attach' option. This way, if you re-attach the geometry from Design Modeler the contacts won't auto recreate themselves.

Thank you for your response!
I've been waiting it so much!!! :D