Isolated regions problem in a single domain case

Cuau · February 19, 2020, 19:16

Hello,
I'm running a very simple case to experiment with momentum source to simulate a pump.
The geometry is two boxes connected by two pipes, the pipe on top is the pump. The whole thing consist of two solids, one is the pump, the other is everything else. See attached pictures.
In CFX-Pre, I have only one domain (that contains the two solids) and one subdomain for the pump.
In SpaceClaim, the parameter "Share Topology" has been set to Merge.
The mesh in the pump is conformal with the rest of the mesh.

Cuau · February 19, 2020, 19:19

... continued (i got 403 Forbiden when I tried to post the whole thing)

I get the following error when I try to run it:
"2 isolated fluid regions were found in domain Domain 1"

I have confirmed in CFX-Post that the isolated region is the pump.
Everything is run from workbench, with a SpaceClaim module, a Mesh module and a CFX module. I'm using ANSYS 2019R3 student license.

I don't know if the problem should be fixed in SpaceClaim, Mesh or CFX-Pre.
Any help would be appreciated

AtoHM · February 20, 2020, 01:32

I assume this can be fixed at any level. In Pre you will need to create a domain interface and select the connected faces for CFX to find the connection.

Cuau · February 25, 2020, 12:27

Hi AtoHM, do we have to define interfaces even if there is only one domain? The idea is to have the momentum source in a subdomain inside my single domain.

AtoHM · February 25, 2020, 13:07

If you mesh the parts separately and don't tell them where they are glued together, you must give a domain interface even if you have both meshes in the same domain, yes.

Cuau · February 25, 2020, 14:06

Ok. In my case, it's meshed together. I create one part in SpaceClaim, which I split into two parts. The shared topology parameter is set to merge. Then I mesh it, and then I open it with cfx pre, all from workbench.

My understanding is that in that case, there are no interfaces since its one domain.
For some reason cfx pre thinks that the different parts are not connected, and I don't know how to fix that.

AtoHM · February 26, 2020, 01:16

I dont use SpaceClaim so I won't be of much help with it. Maybe there are tutorials on youtube or something where the process is described entirely?

Cuau · February 27, 2020, 15:16

I found a solutuion/workaround:
It works when I go through the same process without using workbench. I create geometry with spaceclaim, save the file, open it with mesh, create the mesh, export it to cgns, then import it to cfx-pre. I didn't experiment with other mesh file types, maybe thats the issue with workbench.

AtoHM · February 28, 2020, 01:07

Indeed, the workbench sometimes causes strange behavior of the individual packages, I actually considered recommending you to do it in standalone mode in the first place but figured it should work anyway. Good to know and glad you could sort it out.

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February 19, 2020, 19:19		#2
Cuau New Member Join Date: Feb 2020 Posts: 7 Rep Power: 6	... continued (i got 403 Forbiden when I tried to post the whole thing) I get the following error when I try to run it: "2 isolated fluid regions were found in domain Domain 1" I have confirmed in CFX-Post that the isolated region is the pump. Everything is run from workbench, with a SpaceClaim module, a Mesh module and a CFX module. I'm using ANSYS 2019R3 student license. I don't know if the problem should be fixed in SpaceClaim, Mesh or CFX-Pre. Any help would be appreciated

February 20, 2020, 01:32		#3
AtoHM Senior Member M Join Date: Dec 2017 Posts: 642 Rep Power: 12	I assume this can be fixed at any level. In Pre you will need to create a domain interface and select the connected faces for CFX to find the connection.

February 25, 2020, 12:27		#4
Cuau New Member Join Date: Feb 2020 Posts: 7 Rep Power: 6	Hi AtoHM, do we have to define interfaces even if there is only one domain? The idea is to have the momentum source in a subdomain inside my single domain.

February 25, 2020, 13:07		#5
AtoHM Senior Member M Join Date: Dec 2017 Posts: 642 Rep Power: 12	If you mesh the parts separately and don't tell them where they are glued together, you must give a domain interface even if you have both meshes in the same domain, yes.

February 25, 2020, 14:06		#6
Cuau New Member Join Date: Feb 2020 Posts: 7 Rep Power: 6	Ok. In my case, it's meshed together. I create one part in SpaceClaim, which I split into two parts. The shared topology parameter is set to merge. Then I mesh it, and then I open it with cfx pre, all from workbench. My understanding is that in that case, there are no interfaces since its one domain. For some reason cfx pre thinks that the different parts are not connected, and I don't know how to fix that.

February 26, 2020, 01:16		#7
AtoHM Senior Member M Join Date: Dec 2017 Posts: 642 Rep Power: 12	I dont use SpaceClaim so I won't be of much help with it. Maybe there are tutorials on youtube or something where the process is described entirely?

February 27, 2020, 15:16		#8
Cuau New Member Join Date: Feb 2020 Posts: 7 Rep Power: 6	I found a solutuion/workaround: It works when I go through the same process without using workbench. I create geometry with spaceclaim, save the file, open it with mesh, create the mesh, export it to cgns, then import it to cfx-pre. I didn't experiment with other mesh file types, maybe thats the issue with workbench.

February 28, 2020, 01:07		#9
AtoHM Senior Member M Join Date: Dec 2017 Posts: 642 Rep Power: 12	Indeed, the workbench sometimes causes strange behavior of the individual packages, I actually considered recommending you to do it in standalone mode in the first place but figured it should work anyway. Good to know and glad you could sort it out.