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davidrobinson50 October 8, 2012 02:16

Match control at interface between two separate geometries
1 Attachment(s)

I'm constructing a mesh using ANSYS 14.0 and I'm wondering if it's possible to match the mesh at the interface between two separate geometries. My two geometries consist of a large outer region and a rotating cylindrical region within it (I've attached a sliced image this).

Basically, what I want to do is use a match control to match the mesh density at the interface between the rotating and stationary regions. Unfortunately ANSYS won't let me do this.

Does anyone have any advice to get around this problem?

siw October 8, 2012 02:22

Maybe give this a try:

Open your geometry in DesignModeler and in the Outline listed on the left select these two bodies and RMB to select "Form New Part" that should put them into a multi-body part to make a conformal mesh at the interface.

You should not then have to use Match Control - I don't think that's what Match Control was intended for anyway.

davidrobinson50 October 8, 2012 02:26

Thanks for the reply.

Your solution will match the mesh at the interface, however, because my geometries are now one part I can no longer rotate them relative to each other in Fluent.

I'm attempting to use 'contact sizing' at the moment to see if I can achieve what I'm after.

flotus1 October 8, 2012 10:44


Originally Posted by davidrobinson50 (Post 385419)
however, because my geometries are now one part I can no longer rotate them relative to each other in Fluent.

Sure you can. Just remember to freeze the bodies before forming a new part.

davidrobinson50 October 9, 2012 23:45

Hi thanks for your reply.

Your solution allows me to mesh the interface between the two parts exactly how I want it.

The problem now is that I only have one interface between the two parts. I need two interfaces (one on each part) to define the mesh interface in Fluent. Do you have any suggestions for how to get around this?

davidrobinson50 October 10, 2012 00:06

1 Attachment(s)
If it helps, I've attached a screen shot of the problem I'm having now in Fluent. You can see that there is an interface between the two parts but I can't define it properly.

nkme2007 October 10, 2012 05:51

Hello All,

I want to do analysis of heat transfer from water flowing through pipes submerged inside concrete. I am modelling in GAMBIT and wish to analyse it on Ansys FLUENT.

Can anybody help me out, how to model and simulate?

Does any tutorials exist?

PSYMN October 10, 2012 09:33

@david robinson...

Make sure to create a Named Selection for each body (Rotating Fluid & Stationary Fluid), then proceed to Fluent, it will create a shadow part for you.


You hijacked a bunch of threads, it is annoying and probably won't help with a broad question like that. If you are looking for Gambit/Fluent tutorials, just Google it. The old fluent site had a lot of tutorials, but I forget the link.

nkme2007 October 10, 2012 09:58

I am sorry for the offence.

davidrobinson50 October 10, 2012 20:48


The problem is that because I have frozen the two geometries and formed them into one part, there is now only one surface between the two geometries. Therefore, I can't create a separate named selection for each interface.

Is there something that I am missing here?

PSYMN October 10, 2012 21:01

Yea, don't worry about that (either David or NKME) ;)

David, just move ahead. If the interface named selection is called something like "INTERFACE" and the Named selections for the bodies are either side are given, lets say "FLUID" and "ROTATING_FLUID" then when things go to Fluent, the Bodies will become zones and Fluent will split the interface for you.

Best regards,


davidrobinson50 October 10, 2012 21:22

Thanks for the reply, I'm afraid I still can't get your method to work. Fluent automatically separates the bodies into zones as you advised. However, I still only have one interface at the boundary between the two zones. I need two interfaces so that I can define the mesh interface correctly.

PSYMN October 10, 2012 22:28

Maybe I am forgetting something that usually just do as a matter of course...

If I get a chance, I will do a simple example at some point...

davidrobinson50 October 10, 2012 22:58

Thanks, I would appreciate that :)

john c April 10, 2013 21:35

hey guys,

any update as to how this worked out? this is the exact problem I am running into...I have a similar scenario where I have a rotating domain and a stationary domain and for the interface I can only pick one side. I have two cylinders, one is inside the other, the inside one is the rotating domain while the outside is the stationary domain. When I define my interface I can only pick the outside wall of the inner cylinder but am not able to pick the inside wall of the inner cylinder and define that as an interface also (and then define the interface in fluent).

davidrobinson50 April 10, 2013 21:45

If I recall correctly I was having this problem because I hadn't set up my geometry correctly. I had somehow managed to created a surface that was shared by both the rotating and stationary regions, rather than an individual interface surface for each region.

I'd recommend setting up your geometry again and making sure that the stationary and rotating regions are separate frozen parts. This should give you a separate interface for each part.

Hope this helps..

john c April 10, 2013 21:52

Well I basically have a cylinder inside of a cyliner, the wall of the inner cylinder is acting as the interface, are you suggesting that i add another geometry in between? I have also ready that once I make my way into fluent, and define the interface, fluent will have an option with the wall split into two and then maybe I can define it as an interface? thank you for replying, i really appreciate it.

davidrobinson50 April 10, 2013 22:00

Hmm, do you have a screenshot of your geometry? The way you describe it it sounds like your stationary region is overlapping you rotating region. If this is the case then it won't work (Fluent can't handle overlapping meshes).

When you set up your geometry, your stationary region should be ring-shaped and the rotating region should be a cylinder (that fits inside ring). The stationary and rotating regions should be modelled as two separate, frozen parts. You don't need any additional geometries between the two parts.

I'm not aware of Fluent being able to split a wall in two, but that's not to say that it can't be done..

john c April 11, 2013 02:03

1 Attachment(s)
Yeah you have the right idea...I have an impeller that I imported in as a step file from Solidedge, i then encompassed that with a cylinder that will represent the rotating domain and then encompassed all of that with another cylinder which will be the stationary. Also I have used the boolean subtract command to subtract the impeller so it is no longer a solid inside the rotating domain. Please see attached picture.

So you're saying that I should make the larger of the cylinders ring-like, as in remove the flat surfaces from both ends and only have the curved wall? Thank you once again for the time, I don't think I can put into words how much I really do appreciate it.

john c April 11, 2013 02:07

1 Attachment(s)
Here is an additional picture with the geometry meshed.

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