Ensure we handled the rotational and divergent parts correctly

[jbphyswx]

Helmholtz Decomposition. see https://doi.org/10.1029/2022GL097713.

We need to ensure we have both the 3rd order SF for energy cascade and those Lindborg 2015 transformations from https://doi.org/10.1017/jfm.2014.685 set up and on offer correclty.