CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Visualization & Post-Processing Software > ParaView

[OpenFOAM] saving data in paraview

Register Blogs Community New Posts Updated Threads Search

Like Tree1Likes
  • 1 Post By wyldckat

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 22, 2014, 11:57
Default saving data in paraview
  #1
Senior Member
 
Join Date: Nov 2012
Location: Bavaria
Posts: 145
Rep Power: 14
aylalisa is on a distinguished road
Dear Foamers,

I've calculated kinetic energy from vector field U in paraview with the calculator.
Afterwards I've saved the data (vectorfield U and computed scalarfield K). Before saving process is finished the user needs to choose the field association:
Points, Cells or Field Data.

If I choose 'Points' or 'Cells' I receive four csv.files. The first file contains values of the internal flow field.
The other three files contain values from patches, but not for all patches.

In my test case I've a flow channel with cyclic inlet/outlet (flow-direction) and cyclic patches in spanwise direction. top and bottom patches are defined as walls. To be able to do grading I've created the mesh with two blocks. That way flow domain is horizontally subdivided (at y = 1/2*channel height). Total number of patches = 10.

I've compared number of cells on the patches with number of file entries in the three additional data files. It seems that two of these three additional files contain values for one inlet and one outlet patch (in total I've two inlet and two outlet patches) and the last file contains values of only one wall patch (bottom or top).

I've no symmetry plane defined. Why do I not receive a data file for each patch?

What is the difference between the Field Association options 'Points', 'Cells' and 'Field Data'?
I thought 'Points' give values at cell centroids. But this idea must be wrong because the file contains U component values equal to zero. That indicates that 'Points' lie on the wall where U is zero.
If I choose 'Cells' the data files contain only the components of velocity vector U but no the scalar values of kinetic energy K. Does 'Cells' imply vector components?
And if I choose 'Field Data' the csv files are empty.

Could anybody explain me the options 'Cells' and 'Field Data' ?


Aylalisa
aylalisa is offline   Reply With Quote

Old   May 25, 2014, 08:14
Default
  #2
Retired Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,981
Blog Entries: 45
Rep Power: 128
wyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to all
Greetings Aylalisa,

A detailed explanation on the topic of point data vs cell data is given here: http://www.cfd-online.com/Forums/ope...tml#post446469 post #12

As for "Field data": I haven't fully figure out what it's for, but AFAIK it's not commonly used for OpenFOAM cases.

As for the various CSV files: I believe that you're getting one file per loaded block. In other words, the readers for opening OpenFOAM cases in ParaView, usually associate 1 data block per mesh part, as shown in the attached picture.
If you're not getting all of the CSV files for all of the patches you want, it's very likely that you didn't choose to load all of the mesh parts that your case provides.

Best regards,
Bruno
Attached Images
File Type: png Screenshot from 2014-05-25 12:08:34.png (34.4 KB, 407 views)
deepbandivadekar likes this.
__________________
wyldckat is offline   Reply With Quote

Old   May 28, 2014, 09:56
Default
  #3
Senior Member
 
Join Date: Nov 2012
Location: Bavaria
Posts: 145
Rep Power: 14
aylalisa is on a distinguished road
Hello Bruno,

thank you for your support!

Quote:
As for the various CSV files: I believe that you're getting one file per loaded block. In other words, the readers for opening OpenFOAM cases in ParaView, usually associate 1 data block per mesh part, as shown in the attached picture.
If you're not getting all of the CSV files for all of the patches you want, it's very likely that you didn't choose to load all of the mesh parts that your case provides.
You are right, I chose only three mesh parts including the internal mesh and therefore received 'only' four data files!

With help of the documentation I understand 'point data' and 'cell data'.


I wonder why the files, generated by selecting 'field data', are empty , that makes it hard to derive their meaning.


Aylalisa
aylalisa is offline   Reply With Quote

Old   May 31, 2014, 12:38
Default
  #4
Retired Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,981
Blog Entries: 45
Rep Power: 128
wyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to all
Quote:
Originally Posted by aylalisa View Post
I wonder why the files, generated by selecting 'field data', are empty , that makes it hard to derive their meaning.
If there are no fields in "field data", then is nothing to export to CSV file.

I've done a quick search and it's explained here: http://www.paraview.org/Wiki/VTK/Tut...rage#FieldData - and I quote:
Quote:
FieldData

Arrays attached to the FieldData of a dataset describe global properties of the data. That is, if you want to save the time at which the data were recorded, you would put that value in the FieldData. If you wanted to name the data set, you would also put that in the FieldData. There are no restrictions about the length of arrays that are added to the FieldData.
This simply isn't used by OpenFOAM, when converting data to VTK format.
wyldckat is offline   Reply With Quote

Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[OpenFOAM] How to get the coordinates of velocity data at all cells and at all times vidyadhar ParaView 9 May 20, 2020 21:06
UDF value to large for defined data type Anna73 Fluent UDF and Scheme Programming 9 September 30, 2018 23:18
[General] Advice on post processing compressor blade data in paraview Jack001 ParaView 0 February 4, 2016 18:16
[General] Best way to get data from Python into ParaView MalteJ ParaView 2 August 21, 2013 15:52
How to update polyPatchbs localPoints liu OpenFOAM Running, Solving & CFD 6 December 30, 2005 18:27


All times are GMT -4. The time now is 15:59.