saving data in ACM (and possibly others)

[tommy-engels]

The function of the PREPARE_SAVE_DATA_ACM routine is to store everything we want to write to disk in the hvy_tmp variable.
For example, if the name is ux, then the first component of the state vector is copied to this place in the hvy_tmp array.
This all works fine except for the vorticity, which has in 3D 3 components. The current PREPARE_SAVE_DATA_ACM will not work for that and should be revised at some point. Note the number params%N_fields_saved must in fact include 3 slots for the vorticity in that case.

It may be better to not even provide the possibility to save arbitrary data in wabbit at this point and simply compute derived qty in postprocessing. At least for the ACM, this might be an option.