Rainbow colormaps are bad. I created two GitHub Repositories for better color map choices, courtesy of Kenneth Moreland. They are fluent_colormaps and cfdpost_colormaps for Fluent and CFD Post, respectively.
If any ANSYS reps see this, it'd be super nice if these could be officially implemented into new ANSYS versions!
If you have any questions or comments, please let me know!
Why not just use Rainbow like everyone else?
Generally, Rainbow is used as the color map for visualization, even though it has been proved to be quite poor for data visualization on a number of different levels. Information on this can be seen on Kenneth Moreland's website.
Here's an example of a SBES (hybird RANS-LES) simulation result at a single time step. The domain is axisymmetric with flow going right to left:
It can easily be seen that the brighter blue is drowning out the smaller scale turbulence. The use of a better color map can improve this dramatically:
There are dozens of other color map choices that are an improvement on the standard rainbow. I've compiled a imgur album of examples so that you can easily see the different options.