To compute the mean flow over multiple time steps, the macro
that was suggested would only work for grids of the same size in I,J,K. For
unstructured meshes, that includes I,J, where I is the number of nodes and J is
the number of elements, and the type of elements.

But all is not lost. There are interpolation schemes in Tecplot
that can aid in this computation. If you choose a discretization, and
interpolate each solution onto the same grid, you can use the macro you have
been trying on the interpolated solutions. Note that there are a couple of ways
to do this. In some instances, the inverse distance and krigging can lead to
spurious interpolation errors. What I have found works best is to use linear
interpolation. Now, there is a command you need to add to the configuration
file to improve the quality of the interpolation, including:

$!Interface

Data

{

VolumeCellInterpolationMode = Trilinear

}

You can add this line by outputting the configuration data with
factory defaults to a file. Then, change the interface command, and start
Tecplot with this new configuration file. Or, you can change the system
configuration file, if you have root access.

For very accurate interpolation, since your data is in a plane,
map everything to that plane. Your underlying grid can be an unstructured mesh,
but I prefer to use a structured mesh. If you do not have a structured 2D mesh,
Tecplot also provides the Mesh Generator. You can use this code to generate the
structured mesh in 2D for interpolation purposes. It’s fast and provides
a decent grid for interpolation.

Good Luck.

**From:**
Tecplot_Talk@yahoogroups.com [mailto:Tecplot_Talk@yahoogroups.com] **On Behalf
Of **boulboul_fr

**Sent:** Friday, January 25, 2008 3:45 AM

**To:** Tecplot_Talk@yahoogroups.com

**Subject:** [Tecplot_Talk] Re: Average of instantaneous data on a plane

Hi Stephen,

Thank you for your help. I loaded the statistics Addon but actually

what I want is to compute the mean flow on a plane over a certain

number of time steps. I need to plot contours of mean velocities on a

plane.

I tried to use the macro I found in the forum but since the grid of the

plane is slighlty different from one step to another , the macro didn't

work.