[DesignModeler] Splitting a Circle into 2 regions

Diger · May 8, 2018, 16:46

I have an imported geometry in which I want to split a circle from the surface into 2 separate regions, such that I can label them with individual component names.
The reason is that this circle is an outlet ultimately, and I want to calculate the massflow through each half of the circle separately.

If this is still possible in the post processing let me know, otherwise I need this solution.

Gert-Jan · May 8, 2018, 17:36

This is possible in the CFD-Post. There, you can create a user surface that splits your outlet in two (or in as many as you like).
You have to be aware that the line that splits the outlet, normally will not be in line with your mesh. So, some inaccuracy might play a role. Therefore, it might be a good idea to split your outlet beforehand to have a clear distinction at least.

Diger · May 8, 2018, 17:51

Do I really need to go into CFD-Post, or can I use the post-processing of the Fluent solver which was enough for me until now.

Concerning the Splitting of the Model: Do you know how to do this?

Gert-Jan · May 8, 2018, 17:57

Than it turns into a Fluent question, so I would ask it in the fluent forum.

Splitting the model. Normally you do that in Design modeler or Spaceclaim. In fluent, I don't know. I try to avoid that program as much as possible.

Diger · May 8, 2018, 18:27

So you prefer working with CFX? why???

The previous question of course refered to design modeler. Which function/option do I need to use in order to split a surface?

Gert-Jan · May 8, 2018, 18:35

I was raised using CFX. So that is the main reason. But I think it is more stable, provides easier control over the calculation (monitoring and tuning the run is much easier) and it is a node based solver. So, you can get away with a tet mesh. It is comparable with a polymesh solution using the cell based solver in fluent.
On the other hand, Fluent has more models. So that might be a reason to use fluent. What ever you like.

I stopped using Designmodeler and replaced it for Spaceclaim. Sorry, I can't help you with that.

Diger · May 8, 2018, 19:55

Can you maybe tell me where I precisely need to go in CFD Post to achieve this?
Is it "User Surface"? And then I need to "Intersect With" something?

Gert-Jan · May 9, 2018, 04:09

Out of my head:

1. Create a contour plot
2. Select the outlet as object
3. Use one of the coordinates (X,Y or Z) as local (!) plot variable in the contour.
4. Take 3 levels and press apply
5. Then create a user surface and use one of the levels of the contour.

Level 2 will be one side, level 3 will be the other side.
In this way you can create 2 surfaces at the outlet.
Then using the calculator, you can determine the massflows: massFlow()@User surface 1 & massFlow()@User surface 2

Diger · May 9, 2018, 07:20

1. Create a contour plot
I guess you mean "Contour" right of "Vector" and left of "Streamline"

2. Select the outlet as object
Did that

3. Use one of the coordinates (X,Y or Z) as local (!) plot variable in the contour.
Ah sorry. Why can I just choose any of these 3?

4. Take 3 levels and press apply
What does this mean? # of Contours?

Gert-Jan · May 9, 2018, 07:32

In the pull down menu of the item Variable. You can also click on the three dots. Then you can find your coordinates in the Geometric section.

Gert-Jan · May 9, 2018, 07:33

See example

Diger · May 9, 2018, 07:38

Sorry I think i managed.
Thanks

Actually: Is it also possible to select multiple "contour levels" in the user surface when for instance I started not with 3 but with 10? e.g.: My surface should then be contour level 3,5,8

Gert-Jan · May 9, 2018, 08:18

Sure you can. Just increase the number of contours in your contour plot.
Then create more user surfaces.
See my example where I defined 11 segments on an arbitrary plane in a geometry. For each segment I calculated the massflow.

Diger · May 9, 2018, 08:20

Yeah ok. I mean within 1 user-surface. Creating tons of usersurfaces seemed a bit cumbersome.

Gert-Jan · May 9, 2018, 08:33

Not that I know. But I am sure you can make a script to make multiple user faces. Ask in the CFX-forum. It is likely that people can guide you.

Alternatively, you can save a state file, which is a text file. You can modify this in a text editor, add the user surfaces you need and read it in again into Post. Probably this goes faster than manually adding these by hand in Post.

You can calculate the massflows in a table. The contents of this table is also present in the state file. There you can add the massflows from other user surfaces to make a long list that you can copy to e.g. Excel.

May 8, 2018, 16:46	Splitting a Circle into 2 regions	#1
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	I have an imported geometry in which I want to split a circle from the surface into 2 separate regions, such that I can label them with individual component names. The reason is that this circle is an outlet ultimately, and I want to calculate the massflow through each half of the circle separately. If this is still possible in the post processing let me know, otherwise I need this solution.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Splitting Regions in a Clip	toiago	EnSight	1	July 27, 2015 14:53
splitting regions and defining BC in conjugate heat transfer	skuznet	OpenFOAM Pre-Processing	3	December 9, 2013 05:42
decomposePar -region (OF 2.1) without splitting regions in separate parts	michielm	OpenFOAM Pre-Processing	1	November 15, 2013 06:07
[ICEM] Automatic geometry preparation for hex mesh and circle curve splitting	waiter120	ANSYS Meshing & Geometry	2	May 5, 2013 12:00
Splitting regions	king_steve	STAR-CCM+	1	September 27, 2010 13:48

May 8, 2018, 17:36		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	This is possible in the CFD-Post. There, you can create a user surface that splits your outlet in two (or in as many as you like). You have to be aware that the line that splits the outlet, normally will not be in line with your mesh. So, some inaccuracy might play a role. Therefore, it might be a good idea to split your outlet beforehand to have a clear distinction at least.

May 8, 2018, 17:51		#3
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	Do I really need to go into CFD-Post, or can I use the post-processing of the Fluent solver which was enough for me until now. Concerning the Splitting of the Model: Do you know how to do this?

May 8, 2018, 17:57		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	Than it turns into a Fluent question, so I would ask it in the fluent forum. Splitting the model. Normally you do that in Design modeler or Spaceclaim. In fluent, I don't know. I try to avoid that program as much as possible.

May 8, 2018, 18:27		#5
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	So you prefer working with CFX? why??? The previous question of course refered to design modeler. Which function/option do I need to use in order to split a surface?

May 8, 2018, 18:35		#6
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	I was raised using CFX. So that is the main reason. But I think it is more stable, provides easier control over the calculation (monitoring and tuning the run is much easier) and it is a node based solver. So, you can get away with a tet mesh. It is comparable with a polymesh solution using the cell based solver in fluent. On the other hand, Fluent has more models. So that might be a reason to use fluent. What ever you like. I stopped using Designmodeler and replaced it for Spaceclaim. Sorry, I can't help you with that.

May 8, 2018, 19:55		#7
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	Can you maybe tell me where I precisely need to go in CFD Post to achieve this? Is it "User Surface"? And then I need to "Intersect With" something?

May 9, 2018, 04:09		#8
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	Out of my head: 1. Create a contour plot 2. Select the outlet as object 3. Use one of the coordinates (X,Y or Z) as local (!) plot variable in the contour. 4. Take 3 levels and press apply 5. Then create a user surface and use one of the levels of the contour. Level 2 will be one side, level 3 will be the other side. In this way you can create 2 surfaces at the outlet. Then using the calculator, you can determine the massflows: massFlow()@User surface 1 & massFlow()@User surface 2

May 9, 2018, 07:20		#9
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	1. Create a contour plot I guess you mean "Contour" right of "Vector" and left of "Streamline" 2. Select the outlet as object Did that 3. Use one of the coordinates (X,Y or Z) as local (!) plot variable in the contour. Ah sorry. Why can I just choose any of these 3? 4. Take 3 levels and press apply What does this mean? # of Contours?

May 9, 2018, 07:32		#10
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	In the pull down menu of the item Variable. You can also click on the three dots. Then you can find your coordinates in the Geometric section.

May 9, 2018, 07:38		#12
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	Sorry I think i managed. Thanks Actually: Is it also possible to select multiple "contour levels" in the user surface when for instance I started not with 3 but with 10? e.g.: My surface should then be contour level 3,5,8

May 9, 2018, 08:20		#14
Diger Senior Member Join Date: Nov 2015 Posts: 135 Rep Power: 11	Yeah ok. I mean within 1 user-surface. Creating tons of usersurfaces seemed a bit cumbersome.

May 9, 2018, 08:33		#15
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	Not that I know. But I am sure you can make a script to make multiple user faces. Ask in the CFX-forum. It is likely that people can guide you. Alternatively, you can save a state file, which is a text file. You can modify this in a text editor, add the user surfaces you need and read it in again into Post. Probably this goes faster than manually adding these by hand in Post. You can calculate the massflows in a table. The contents of this table is also present in the state file. There you can add the massflows from other user surfaces to make a long list that you can copy to e.g. Excel.