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Interpolate Data From User Defined Line


This video shows how to load an arbitrary data set into Tecplot 360 and interpolate the arbitrary data to the existing data using the ONERA M6 wing.
Download data and layout files (5.9MB ZIP)

Note that in the video, the Onera M6 wing data have already been loaded. To load this data, go to File > Load Data Files and use the Tecplot Data Loader to navigate to the data and load OneraM6_SU2_RANS.plt.

  1. First, we’ll take a look at our data set by going into Data > Data Set Info. We have two zones and it’s important to note that the variables have a max and min value associated with each zone.
  2. Let’s now take a look at our arbitrary data. We see that it’s simple XYZ data. We’ll now load this by going into File > Load Data Files. Select the Text Spreadsheet Loader, select the file ArbitratyPoints.txt. Open it and choose Append data to active frame.
  3. We can verify that our data were appended by going back into Data Set Info. We see that zone 1 is our loaded data and we can rename it by double-clicking on the name. We’ll change the name to “Arbitrary Points.” We see that the variables, except x, y, and z, in the arbitrary points zone do not have max and min values. This is due to this zone containing passive variables which contain no data. We can visualize our Arbitrary Points zone by turning on mesh. This black line represents our zone.
  4. Let’s now interpolate our data, bringing the variable data from the source zone or zones to the destination zone. To do this, we go into Data > Interpolate. There are three interpolation options:
    • Linear interpolation like it sounds uses a linear interpolation.
    • Inverse-distance interpolation uses a distance based weighting.
    • Kriging is more complicated as it uses a Gaussian weighted average for any given point.

    Note that as you advance in complication of calculation you also increase the time it takes to calculate the solution. See the Tecplot 360 User Manual for more information about the different methods.

    We will use the inverse-distance for this example. Because the line is offset from the trailing edge, we don’t need to interpolate from the wing surface. We want to interpolate from the Fluid Volume Source zone to our Arbitrary Points Destination zone.

  5. We can verify that our interpolation was successful by looking at our Data Set Info again. Now when we click through our variables for the arbitrary points zone, we see that we now have max and min values associated with each variable.
  6. We can now write out the data to a CSV file by going into Tools > Write Data as Formatted Text. To export only the data we interpolated, uncheck All and choose Arbitrary Points. To export only x, y, z, and mach variables, uncheck All and select x, y, z, and mach. Click OK and name the file InterpolatedData and Save to save the CSV file.(You can also export in Tecplot ASCII format text file using the File > Write Data File menu option.)
  7. When the InterpolatedData.csv file is opened outside of Tecplot, all of the chosen variables for the arbitrary zone have been exported.

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