Hi, I´m trying to simulate the EIS of PEM fuel cell using the Equation-Based Modeling (Weak Form PDE). The used PDE equation is the Diffusion equation, with Butler-Volmer equation to determine the flow based on Faraday's Law. After using two steps study (stationary and frequency perturbation), linper() operator to mark the AC contribution as a harmonic perturbation , the impedance have been calculated as following: Z = lindev(V)/lindev(i) Tring to understand exactly how the operator lindev works (I already read the description in Reference-User-Guide), and whether I built my model correctly, I built another model, but this time a linearization of the Butler Volmer equation (not the formula in Batteries & Fuel Cells Users Guide) is used and the linper(), lindev() operators had been dispensed. Of course, instead of a frequency perturbation study I used a normal frequency domain study, but still don´t get the same results from the two models. Any idea where I may have made a mistake? Could someone please explain (maybe with example) how exactly the operator lindev works?
thanks in advance
Mohammad