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Point plotting within a volume

Posted 12 mars 2017, 18:49 UTC−4 Version 5.2a 5 Replies

Brian Henry
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Hello, thanks for looking at this,

I want to get tabled results at a certain point within my model. I create my multiphysics simulation by first importing a mesh from NASTRAN, and then simulating (so I normally can't create points from geometry this way).

Is it possible to take the geometry I get from a mesh import, select a point in 3D, and then get a output value (in my case: pressure)? I can view the volume and surface normally, but this is for some post processing.

Thanks for your help!
5 Replies Last Post 28 mars 2017, 12:46 UTC−4
Jeff Hiller COMSOL Employee

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Posted: 9 years ago 13 mars 2017, 08:08 UTC−4
Hello Brian,
Have you tried creating a Cut Point 3D data set and using that for your post processing?
Best regards,
Jeff
Hello Brian, Have you tried creating a Cut Point 3D data set and using that for your post processing? Best regards, Jeff
Brian Henry
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Posted: 9 years ago 15 mars 2017, 14:08 UTC−4
Hello,

I'm looking for something like this:

www.comsol.com/community/forums/general/thread/35590/

where I can input a series of x,y and z coordinates and get the values that way.

I tried to do two things to facilitate this: one, what was mentioned in that with the scatter volume (but I needed to input a radius, not sure what that was about) and also through exporting a grid of points and finding the closest value in the grid to the actual coordinate I have, but I wasn't able to export a fine enough grid for what I wanted due to memory problems.

Ideally I want to get values at whatever x,y,z coordinate I want. If I have to do it manually I will, albeit it will be a long annoying process. Is there a way to do this?

Thanks!
Hello, I'm looking for something like this: https://www.comsol.com/community/forums/general/thread/35590/ where I can input a series of x,y and z coordinates and get the values that way. I tried to do two things to facilitate this: one, what was mentioned in that with the scatter volume (but I needed to input a radius, not sure what that was about) and also through exporting a grid of points and finding the closest value in the grid to the actual coordinate I have, but I wasn't able to export a fine enough grid for what I wanted due to memory problems. Ideally I want to get values at whatever x,y,z coordinate I want. If I have to do it manually I will, albeit it will be a long annoying process. Is there a way to do this? Thanks!
Jeff Hiller COMSOL Employee

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Posted: 9 years ago 15 mars 2017, 14:39 UTC−4
Hi Brian,
It sounds like you are after a Cut Point 3D data set.
If the issue is that you have many such points, as suggested by the last sentence, then you could create an app to read the coordinates for all the points from file and automate the process of creating the data sets and evaluating your field (pressure) at those points.
Or you could do essentially the same via MATLAB if your license includes LiveLink for MATLAB.
I am sure there are a bunch of other ways.
Best,
Jeff
Hi Brian, It sounds like you are after a Cut Point 3D data set. If the issue is that you have many such points, as suggested by the last sentence, then you could create an app to read the coordinates for all the points from file and automate the process of creating the data sets and evaluating your field (pressure) at those points. Or you could do essentially the same via MATLAB if your license includes LiveLink for MATLAB. I am sure there are a bunch of other ways. Best, Jeff
Gunnar Andersson COMSOL Employee

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Posted: 9 years ago 16 mars 2017, 03:33 UTC−4

Ideally I want to get values at whatever x,y,z coordinate I want. If I have to do it manually I will, albeit it will be a long annoying process. Is there a way to do this?


If you have many (x, y, z)-triplets in a file, then I suggest the following approach:
- Create a 3D Cut Point data set.
- Set Entry method =From file.
- Browse to the file containing your points. The file format is assumed to be one line for each point. If your file has some other format, then you have to preprocess it in some external program.
- Results > Export: Create a Data export.
- Select the cut point data set created above.
- Choose the expression(s) to evaluate and browse to an output file. Click on Export.

An alternative is to use a Results > Derived Values > Point Evalution feature. Then you see the results in a table in the GUI. This approach works for a small to moderate number of points, but for a large number of points it becomes unwieldy.
[QUOTE] Ideally I want to get values at whatever x,y,z coordinate I want. If I have to do it manually I will, albeit it will be a long annoying process. Is there a way to do this? [/QUOTE] If you have many (x, y, z)-triplets in a file, then I suggest the following approach: - Create a 3D Cut Point data set. - Set Entry method =From file. - Browse to the file containing your points. The file format is assumed to be one line for each point. If your file has some other format, then you have to preprocess it in some external program. - Results > Export: Create a Data export. - Select the cut point data set created above. - Choose the expression(s) to evaluate and browse to an output file. Click on Export. An alternative is to use a Results > Derived Values > Point Evalution feature. Then you see the results in a table in the GUI. This approach works for a small to moderate number of points, but for a large number of points it becomes unwieldy.
Brian Henry
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Posted: 9 years ago 28 mars 2017, 12:46 UTC−4
Hello, sorry for responding late to this, I was at a conference the past week,

The former worked perfectly, thanks!
Hello, sorry for responding late to this, I was at a conference the past week, The former worked perfectly, thanks!

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