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Validation Study: How do I plot wind tunnel data (*.dat) in Paraview

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Old   July 28, 2011, 15:33
Question Validation Study: How do I plot wind tunnel data (*.dat) in Paraview
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Alex
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I'm new to CFD openFOAM so I'm running through a validation case to sharpen my skills.

The windtunnel data for the Ahmed Body is taken from here

The *.dat files contain data points for given planes. How to I plot them and interpolate it over the plane to compare my results to the windtunnel?
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Old   August 3, 2011, 11:27
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Update:

Ok I managed to import the data after cleaning it up a little in excel and saving it as a CSV file (comma delimited)

Paraview can open CSV files as a table. Then I applied the Filter > TableToPoints to get points. However I wasn't able to see them until I clicked on the split "horizontal button" on the right and chose a 3D view.

Now I have the points where I want them, but I can't manage to get a surface from the points. Any ideas?
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Last edited by bigbang; August 3, 2011 at 12:27. Reason: wrong procedure described to reach goal
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Old   August 4, 2011, 15:15
Default matlab to the rescue
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OK so I finally managed to get a surface from my points.

Unfortunately it was not by means of free software. I used matlab to interpolate the points over a structured grid and then plotted the result. First you must load your data into matlab under 3 arrays. I used 'x', 'y' and 'z'. Where x and y were the coordinates and z was the magnitude of the velocity.

Code:
ti = -250:1:250;
tj = 28:1:538;
[qx,qy] = meshgrid (ti,tj);
F = TriScatteredInterp(x,y,z);
qz = F(qx,qy);
R = maprasterref();
mapshow(qz, R, 'DisplayType', 'surface');
And after adjusting the plot using plotting tools you can see the attached result.
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File Type: jpg ahmedBody25_data_YZ_X0.jpg (21.3 KB, 27 views)
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Old   August 5, 2011, 04:30
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Alex, have you tried the TableToStructuredGrid filter instead of TableToPoints?
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Old   August 5, 2011, 09:00
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Yes. Unfortunately I get a long error message about the number of rows.

I imported my data from CSV and it all comes in clean with the headers. There are 911 datapoints.

Then I select the TableToStructuredGrid filter and enter the range of my data and select the columns for x, y and z coordinates:
x {0,0}
y {-250,250}
z {28, 538}

I apply and get the following error:

Code:
ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Graphics/vtkTableToStructuredGrid.cxx, line 97
vtkPTableToStructuredGrid (0x2621f90): The input table must have exactly 256011 rows. Currently it has 911 rows.


ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Filtering/vtkExecutive.cxx, line 756
vtkPVCompositeDataPipeline (0x2623220): Algorithm vtkPTableToStructuredGrid(0x2621f90) returned failure for request: vtkInformation (0x26ccb40)
  Debug: Off
  Modified Time: 82398
  Reference Count: 1
  Registered Events: (none)
  Request: REQUEST_DATA
  ALGORITHM_AFTER_FORWARD: 1
  FROM_OUTPUT_PORT: 0
  FORWARD_DIRECTION: 0




ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Graphics/vtkTableToStructuredGrid.cxx, line 97
vtkPTableToStructuredGrid (0x2621f90): The input table must have exactly 256011 rows. Currently it has 911 rows.


ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Filtering/vtkExecutive.cxx, line 756
vtkPVCompositeDataPipeline (0x2623220): Algorithm vtkPTableToStructuredGrid(0x2621f90) returned failure for request: vtkInformation (0x26cc300)
  Debug: Off
  Modified Time: 85434
  Reference Count: 1
  Registered Events: (none)
  Request: REQUEST_DATA
  ALGORITHM_AFTER_FORWARD: 1
  FROM_OUTPUT_PORT: 0
  FORWARD_DIRECTION: 0




ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Graphics/vtkTableToStructuredGrid.cxx, line 97
vtkPTableToStructuredGrid (0x2621f90): The input table must have exactly 256011 rows. Currently it has 911 rows.


ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Filtering/vtkExecutive.cxx, line 756
vtkPVCompositeDataPipeline (0x2623220): Algorithm vtkPTableToStructuredGrid(0x2621f90) returned failure for request: vtkInformation (0x26cc300)
  Debug: Off
  Modified Time: 85468
  Reference Count: 1
  Registered Events: (none)
  Request: REQUEST_DATA
  ALGORITHM_AFTER_FORWARD: 1
  FROM_OUTPUT_PORT: 0
  FORWARD_DIRECTION: 0




ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Graphics/vtkTableToStructuredGrid.cxx, line 97
vtkPTableToStructuredGrid (0x2621f90): The input table must have exactly 256011 rows. Currently it has 911 rows.


ERROR: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Filtering/vtkExecutive.cxx, line 756
vtkPVCompositeDataPipeline (0x2623220): Algorithm vtkPTableToStructuredGrid(0x2621f90) returned failure for request: vtkInformation (0x26cc300)
  Debug: Off
  Modified Time: 85506
  Reference Count: 1
  Registered Events: (none)
  Request: REQUEST_DATA
  ALGORITHM_AFTER_FORWARD: 1
  FROM_OUTPUT_PORT: 0
  FORWARD_DIRECTION: 0




Warning: In /home/opencfd/OpenFOAM/ThirdParty-2.0.0/ParaView-3.10.1/VTK/Filtering/vtkDataObject.cxx, line 910
vtkTable (0x2549d40): Attempted to ShallowCopy from null.
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File Type: jpg step1.jpg (62.1 KB, 22 views)
File Type: jpg step2.jpg (61.4 KB, 19 views)
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