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Variable Combination and Alias File


This video demonstrates how to use the variable combination dialog and the variable alias. 

In this tutorial we will be loading and merging the variables of two files: 1) experimental wind tunnel results, and 2) CFD for the Onera M6 wing. These are the same files used in the External Aero video on comparing data. In that video we carefully named the variables to ensure they loaded properly.

However now in Tecplot 360 2017 R1 we can load the test data directly.

The first step in this process is downloading the data files directly from the NASA site which provides information on the Onera M6 test data.

Next, we will append this directly to our already open CFD data available in the Tecplot 360 installation. When we select the Append data to active frame option, this opens the Variable Load and Combine dialog because the variable names do not directly match those of the existing dataset. We can see all of the variables that exist in the CFD dataset in the Variables to load column, but the data from the incoming test data are on the left in Available Variables.

There are two methods to perform the combination of variables.

Method 1

  1. Select Cp in the Available Variables and Pressure Coefficient from the Variables to Load column and select Combine. This brings Cp over and merges it with a semi-colon to be loaded into the same variable.
  2. Select X/L, Y/b and Z/L and click Add Selected, which will append these to the end of the Variables to Load list. It is possible to combine multiple variables simultaneously, but we are appending these rather than combining them with the existing x, y, and z variables as they have been normalized using the dimensions of the wing.
  3. Select OK and go to Data set info to ensure the variables were loaded as instructed.

Method 2

The second method uses an Alias file. You can find an example in the base directory of your Tecplot 360 Installation. This Alias file is particularly useful when combining multiple variables at the same time. Here we have added Cp;Pressure_Coefficient. When the appending process is repeated and Apply is selected, the variables will be automatically combined. Note that normalized dimension variables still need to be added.

Both methods for combining variables can be done only while appending a single file at a time.

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