If You have mathematical description of this phenomena (including boundary
condition) we can generate its equivalent model for SPICE or VHDL-AMS using
RESCUER.

The RESCUER software has been developed by me, prof. A. Napieralski and dr.
M. Napieralska, and it is dedicated to multi domain model generation into
SPICE, VHDL-AMS and others simulation environments. Only the PDAE or PDE
description are necessary (for more see M. Zubert, M. Napieralska, A.
Napieralski. RESCUER  The new solution in multidomain simulations,
Elsevier, Microelectronics Journal 31 (11-12) (2000) pp. 945-954) and M.
Zubert, A. Napieralski, M. Napieralska. The Application of RESCUER
Software to Effective MEMS Design and Simulation, Bulletin of the Polish
Academy of Sciences  Technical Science, No. 4, Warsaw, November 2001).

The most of Electrolytes phenomena can be simulated using Poisson and
diffusion equation (eq. its "micropumps").
Best regards,
Mariusz Zubert