Nernst-Planck module in recent versions

[majin....@gmail.com]

Dear Glenn,

I'm modelling transport in clay rocks and would like to use the Nernst-Planck implementation in more recent PLFOTRAN versions. I notice that the installation (e.g., v7.0) comes with "transport_np.F90", and I can use "NERNST_PLANCK" keyword under OPTIONS without any problem/warnings. 

There seemed to be a small bug on tortuosity (scalar instead of tensor, Line 85 & 86), after fixing that it seems to give reasonable results, so I'm trying to benchmark it against Alt-Epping et al., 2015 and 2018. The results are fairly close, but there seems to be some discrepancy at the boundary with the other models when using ZERO_GRADIENT or NEUMANN for transport BC.

I understand that the NERNST_PLANCK module is not in the official documentation, but may I ask if it is somehow still maintained or tested? 

Many thanks,

Jin