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-   -   Creating multiple region (http://www.cfd-online.com/Forums/star-ccm/78468-creating-multiple-region.html)

niazaliahmed July 22, 2010 09:53

Creating multiple region
 
How to create a geometry which has two regions?

nomad July 23, 2010 13:03

You should expound on that question so that someone can actually help you.

MartiJ August 11, 2010 12:01

I have a question about boundaries and using them to create regions.

Do I need complete set of boundaries to create a new region inside an existing one?
I mean, do the boundaries have to set up a closed volume (cube, sphere, some abstract volume etc.)?

Thanks in advance!

sreenivas August 16, 2010 05:00

Hi
 
You need not close the boundaries in single region but all the regions should be closed to make it a complete closed volume

MartiJ August 16, 2010 05:15

Okay,

but I don't have the regions next to each other.

Imagine the case when you have a cylindrical region inside a bigger pool (cube or whatever). I need to define that this cylinder is e.g porous.

So, question is: is it possible to describe/define/constrain this cylindrical porous region by, lets say, selecting only the side surface of the cylinder and not the bottom and top surfaces. So it is just open-ended (like a pipe). Will this procedure give me a new region or do I need to use/have the top and bottom surface too, to create a cylindrical region inside a bigger one..

Bit confusing, but I need to get things clear..:)

BR.

sreenivas August 16, 2010 05:50

Hi
 
STAR still will treat this as the valid region but porous representation of cylinder is not valid until you select remainig surfaces.The best thing is to do two diffrent volume meshes and create an interface between these two.

MartiJ August 16, 2010 06:11

Oh, I see.

One thing, I need to use the existing mesh (can't mesh again any region).

Other thing, I have only the mesh (not the geometry parts) and a number of boundaries pre-defined in it (I just can ask mesh creators to add some boundaries into the mesh).

So, if I really need to define an inner region with different properties, then I need to have boundaries closing this region (cylinder side, top and bottom surfaces e.g.) ?

EWeird thing is, every time I define a region like just by selecting, for example, two boundaries, after saving and reopening the model, this defined region is cut out from rest of the region and it is impossible to plot it anymore (just can not see it, gone). Why?

Anto September 22, 2010 11:59

I think you should create different regions (I mean one for the porous medium and other regions for the remaining fluid cells). All the regions must be closed. you have to "convert to interface" (right clicking on them) the surfaces that limit the porous medium . automatically a copy of the interfaces created will be produced. these interfaces must be part of the region containing the porous medium and of the region surrounding.

As far as the visualization problem, you have to create a new mesh scene and in this scene you will be able to see all your model!


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