How can I bring up the interior option in the fluent ， I can not find it？
 

How can I bring up the interior option in the fluent ， I can not find it？

You can't find it because it's not supposed to be there. Boundary faces can't be interior type.


The question is, why you are trying to change to interior in the first place something that cannot be interior?

But the middle vertical line is in the fluid domain， which should be as an interior？
 

But the middle vertical line is in the fluid domain， which should be as an interior？

Interior
 

Fluent does not care about the location of the boundary, rather about the sharing of the boundary. If a boundary belongs to only one cell, then it is external boundary and if it belongs to two cells then it is internal. Interior is an internal type. Fluent is reading the boundary as external because you have non-conformal mesh at that location. To make it conformal, you have to ensure that both of the bodies, i.e., the one on the left and the one on the right of the said boundary belong to same part. Currently, if you check under Geometry within Meshing, each body has separate part. So, go back to CAD and ensure that the bodies belong to same part. The other option you have, within Fluent, is to convert both boundaries into interface and then create a mesh interface. You do have two boundaries at that location where you expect one.

Yes, each body has separate part in the Geometry within Meshing, but I have defined
 

Yes, each body has separate part in the Geometry within Meshing, but I have defined them as a whole in the named selection, and it succeed turned into a single zone in the fluent, why it cannot regard as interior?

Secondly, how can I define them in the fluent, should I match them when the two parts are fluid zone?

You see how they are red? That's why they can't be interior.


If you want it to be an interior, it needs to be black. Notice how all the interior faces are drawn in black lines.


Maybe you have two single sided boundaries. But the fact that you've only referred to it as a single boundary and haven't told us that there isn't two boundaries leads me to believe that you think you only have one boundary despite the fact that having a single sided boundary isn't valid in this configuration (you must have two). So I don't know. Really can't tell from a little snippet what your setup is.


If you have two single-sided boundaries you can fuse them together.

What is single sided boundaries? The red line have two zones in the left and right.
 

What is single sided boundaries? The red line have two zones in the left and right. How can I change the red lines to black lines?

which soft do you use for meshing?

if it is workbench mesher -> in geometry module put all our zones into one part -> go to mehser module and create mesh

I know what you mean， but I want to make the mesh change not too big beside the infla
 

I know what you mean， but I want to make the mesh change not too big beside the inflation? You see the image, the nearest size beside the inflation is too big, but I cannot control it in the whole mesh option, how can I deal with it ?