transport equation

CMB

Hi, I am trying to model an electrochemical device with v3.15. In order to achieve a conservation of charge I have to define a different continuity equation for the potential distribution inside a solid region (i.e. domain of solid cells). The potential does not follow traditional d/dxi (roi ui) = 0 but (d/dxi)^2 (poti) = 0, (i being the x,y,z, ro density, u being u,v,w and pot the potential) this is Laplace's equation. Is it possible to apply this in Star?, As far as I am concerned sormom.f allows you to modify the momentum equation but what about the continuity equation for conduction in a solid block? Would appreciate any suggestions. Many thanks, CMB