## Converting Variables Between Cell Centered and Nodal

Question: How do I convert a cell centered variable to be nodal, or vice versa? Solution: This can be done by creating a new variable in the Specify Equations dialog (Data>Alter>Specify Equations). By using the new var location field, a new variable equal to an existing variable can be created with values stored in either location. For example, say a dataset has a cell centered variable named Velocity: To convert […]

Question: I am running out of memory rendering my fine-mesh data. How do I read-in a smaller, decimated version of my ordered dataset into my layout? More details: If you are working on a computer with limited resources, some processes can surpass the available computer memory. If you are unable to add more RAM, this can cause Tecplot to slow or, at worst, crash. Try this solution if some actions […]

## Changing a Contour Legend Variable Name

Question: How do I change the contour legend header text? See Figure 1. Solution: Tecplot 360 2021 R2 and newer: Renaming the legend text header from a contour variable to custom text can be done easily via the Contour & Multi-Coloring Details dialog. 1) In Tecplot 360, go to Plot>Contour/Multi-Coloring… 2) Select the Legend tab and see the Header options at the bottom (see Figure 2). 3) Switch the Header […]

## Explanation of Cell-Centered data when using NumPy Arrays in PyTecplot

Problem: In PyTecplot, why is the length of my array of cell-centered data of an IJK ordered zone (Imax)*(Jmax)*(Kmax-1) instead of (Imax-1)*(Jmax-1)*(Kmax-1)? For example, from a zone with 5x4x3 nodal values, I expect my cell-centered variable array to have a length of 4x3x2 = 24; however, the cell-centered variable array has a length of 40, (5x4x2 = 40). In other words: zone.num_elements == 24 len(zone.values(“CellCentered”)) == 40 Shouldn’t these be […]

## Calculating Grid K Normal Nodal Values

Question: The symmetry of nodal Grid K Unit Normal values differ from the comparable cell-centered values (see Figure 1). How are nodal Grid K Unit Normal values calculated?1 Explaining the Question: In Figure 1, at nodes 1, 6, 11, 16, and 21 the X Grid K Unit Normal vectors are equal. However, on the data row below it (nodes 2, 7, 12, 17, and 22), the components of the X […]

## How to Trim Triangulations

Question: How do I prevent the triangulation feature from spanning concave regions of my plot with triangles? Solution: Extracted polylines can be used as boundary zones to limit the triangulation. In particular, these polylines can be used to prevent triangles from spanning concave regions during 2D triangulations. The following procedure utilizes these polylines to trim a triangulation of unorganized data to the desired shape: 1) Load the data to be […]

## Weighted versus Arithmetic Averages and Tecplot

Question: Why is there a difference in Tecplot’s integration average results and the average, or mean, I am calculating over all the data values? Example:  I have nodal data and I want to calculate average U velocity on the following domain (see Figure 1). When I use the integration average feature (Analyze>Perform Integration…>Average>U), I calculate 38.90 m/s. But when I calculate the average over all the nodal U values in […]

## Creating Streamtraces on a No-slip Boundary Surface with Multiple Surrounding Volume Zones

Problem: How do I create streamtraces on a no-slip boundary surface with multiple surrounding volume zones? In more detail: In the User’s Manual in the section titled “Surface Streamtraces on No-slip Boundaries”, it describes how to create these surface streamtraces in the context of an ASCII file with one parent (volume) zone. However, if other data file types are used or multiple parent zones, these instructions do not apply. Solution: […]

## Error messages compiling Fortran source code using gfortran on Linux

Problem: I get error messages when I try to compile Fortran source code using gfortran on Linux, even though I installed all the necessary “build-essential” gfortran libraries. Unable to compile Fortran source code using gfortran on Linux. Solution: If you are getting error messages when compiling the Fortran source code consider the following. First, the order of calls in the command line is important.  Using Tecplot’s simtest.f90 Fortran source code […]