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How to divide the region for 3D geometry in ANSYS CFD Post

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Old   November 26, 2014, 22:21
Default How to divide the region for 3D geometry in ANSYS CFD Post
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Naimah
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Hi,

I have a complex and irregular shape of the geometry (Please find the attached file)
May I know, how to divide the geometry into different region and calculate for the volume for each region.

Thank you

Naima
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Old   November 27, 2014, 10:22
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Hi,

Any chance you divided the domains before the simulation? In CFX Post you can put "=volume()@S1" in a table to calculate the volume of a domain, where 'S1' is your domain name. If it is just one domain, then I don't know how to do this in Post..

If you have the CAD-files where they are specified as different parts, you could specify them as different domains in CFX-pre and then run the simulation. Then you can gather information for a specific domain.
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Old   November 28, 2014, 00:23
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Thank you KWG for the useful information.

I have tried out the example of equation that you had given.
Let say I want to calculate the volume of velocity lambda-2 in a domain name as volume 2.

But the error message pop up (Please find the attached file).
May I know, how to solve for this.

Thank you again

Naimah
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Old   November 28, 2014, 04:45
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Hi,

Your second picture (which says syntax error) is because you shouldn't use the ''='' when you write an expression. Your first picture, from what I understand, is that CFX is expecting zero arguments in the formula for volume. You put "velocity lambda-2" in the expression, but you should just leave it blank.

You can either write the formula in a table (picture 1) or as an expression (picture 2) to calculate the volume of a domain. Note that in the expression you don't use the "=".

Let me know if this is exactly what you want and if this solves your problem.
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Old   November 28, 2014, 05:24
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Hi KWG,

It is very helpful. Thank you so much.

I have 1 more question,let say I have region of interest (ROI)(as in the circle in the attached file).
I can calculate the volume of that region based on the method that you showed.
If I want to calculate the volume of variable eg velocity lambda-2 at certain threshold at that ROI, how i am going to do that? Is that Possible?

Thank you

Naima
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Old   November 28, 2014, 05:43
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I don't think that is possible. From what I found in the CFX reference guide is that you cannot define any argument in the volume formula. I am also not familiar with this variable velocity lambda-2, what does it represent?



From the CFX Reference Guide:
14.5.29. volume
Calculates the volume of a 3D location.
volume()@<Location>

where:
<Location> is any 3D region (such as a domain or subdomain). An error is raised if the location specified is not a 3D object. For details, see volume (p. 177).
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Old   November 28, 2014, 05:54
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Thank you KWG,

As far that I understand lambda-2 is the indication which part is consider as a vortex.
Actually my main interest is to know whether the volume of this lambda-2 at certain part can be calculated or not.
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