Improve parameter interface

[jbreue16]

For version 6, we should improve our parameter interface and make it more consistent.
See also CADET-Specification #3

• Improve particle interface: group PAR_TYPE_xxx which holds all particle parameters like radius, pore diffusion, binding.
• In 2D models: Change COLUMN_DISPERSION to COLUMN_DISPERSION_AXIAL
• make the velocity/cross section area/flow rate interface unique. Option1: remove velocity field, require cross_section/radius and add flow direction field.

[schmoelder]

make the velocity/cross section area/flow rate interface unique. Option1: remove velocity field, require cross_section/radius and add flow direction field.

I would vote for removing the velocity field. While this is the parameter that is used in the equations, it can change depending on the flow rate (which is a function of the system connectivity matrix), whereas the cross section area cannot. Also, it is more consistent when dealing with radial flow models.

[lieres]

I vote for keeping it to maintain backward compatibility and to accustom users who access CADET-Core directly (and without using systems of unit operations).

[schmoelder]

I agree that backward compatibility should be maintained where possible. But we could still remove it from the "official" interface.

By the way, is it even possible to still use a column without a system in CADET-Core or is it just a system with one unit (that's how it's handled in CADET-Process)?

[jbreue16]

Do we really want to maintain old and thus multiple interfaces? that'd theoretically require testing of all combinations of interface options.
Users can still use old cadet versions, but if they want to use new (free!) features, we can expect them to adapt?

[schmoelder]

I agree but that's not for me to decide. 😅

[lieres]

We can discuss this on a case by case basis. For the reasons mentioned above, I would like to keep the linear flow rate.