A numerical study on preconditioning and partitioning schemes for reactive transport in a PEMFC catalyst layer

A numerical method used to simulate PEMFC catalyst layer transport and electrochemistry is described. The set of nonlinear equations is discretized using the finite volume method and solved using an inexact Newton method. A block “ILU porous” preconditioner is used to precondition the linear system. A “porous partitioning” scheme is used to partition the domain for parallel processors. Geometries with low porosities are found to require a much smaller number of iterations for convergence compared to geometries with high porosities. The porous partitioning scheme is shown to outperform the standard partitioning scheme for cases run with more than 4 processors. The block “ILU porous” preconditioner was not found to be more effective than the block ILU(1) preconditioner. Finally, the importance of using rigorous convergence criteria in these simulations is demonstrated by comparing the computed total consumption values of different species at different nonlinear rms tolerance values.