Caching occurs on the local computer and, if you are reading from a network drive, on the remote file server. When you read a file the operating system will save selected portions of the file in a cache so that subsequent reads of the file are faster. Whenever you measure performance you need to take disk caching into account. This also means the time to read the data can vary substantially with the type of plot you are doing, and the timings given here are for the specific plot that I have created – an isosurface of Cp = -2.0. The “read” operation only reads the file headers. Both SZL and, to a lesser extent, PLT delay the loading of data until you select an object (slice, isosurface, or streamtraces) to display. Note that the time measurements include both reading the file and generating the image.

The plot is the geometry of the aircraft and the Cp = -2.0 isosurface. The surface cells are stored in a separate PLT file which is read in at the same time as the SZL, PLT, or DAT file. The NASA Trapazoidal wing case has 204 million finite-element cells in the volume zone, and another 5.1 million surface cells to define the geometry. I thought it would be useful to compare the file size and Tecplot load times of these file types for a common CFD use case – the NASA Trapezoidal wing. NASA Trap Wing – isosurface of Cp = -2.0.

Tecplot data format example