Simulations were performed to exami

Simulations were performed to examine the effect of wetting contact angle, pressure gradient and surface tension on water transport patterns and water saturation in the catalyst layer. The two sample simulations in Fig. 2 illustrate the effect of increasing hydrophobicity. The left hand side depicts all three phases (water, air, and solid) and the right hand side the corresponding water iso-surfaces. The water penetration patterns reveal a complex fingering process. The results elucidate the significant effect of wettability on dynamic patterns and equilibrium water distribution in catalyst layers. The water transport patterns evolve from “stable displacement”to pure “capillary fingering“. Transition of the water transport pattern from a capillary fingering regime to a stable displacement regime occurs at Lower contact angles result in higher saturation levels and would translate in increased risks of flooding in an operating fuel cell. Conversely, increasing the wettability potentials reduces significantly the transport of water in the domain. The figure also shows that maximum intrusion occurs in conjunction with larger pores. This is consistent with available experimental observations of water transport in hydrophobic electrodes.