  Fluid flow through layered materials with different wetting behavior is
observed in a wide range of applications in biological, environmental and
technical systems. Therefore, it is necessary to understand the occuring
transport mechanisms of the fluids at the interface between the layered
constituents. Of special interest is the water transport in polymer electrolyte
membrane fuel cells (PEM FC). Here, it is necessary to understand the transport
mechanisms of water throughout the cell constituents especially on the cathode
side, where the excess water has to be removed. This is crucial to choose
optimal operating conditions and improve the overall cell performance.
Pore-scale modeling of gas diffusion layers (GDLs) and gas distributor has been
established as a favorable technique to investigate the ongoing processes.
Investigating the interface between the hydrophobic porous GDL and the
hydrophilic gas distributor, a particular challenge is the combination and
interaction of the different material structures and wetting properties at the
interface and its influence on the flow. In this paper, a modeling approach is
presented which captures the influence of a hydrophilic domain on the flow in a
hydrophobic porous domain at the interface between the two domains. A
pore-network model is used as the basis of the developed concept which is
extended to allow the modeling of mixed-wet interactions at the interface. The
functionality of the model is demonstrated using basic example configurations
with one and several interface pores and it is applied to a realistic GDL
representation in contact with a channel-land structured gas distributor.
