Mechanistic and optimization based analysis of bio inspired multiscale flow fields for water management in PEM fuel cells

This work presents a mechanistic and optimization-based analysis of bio-inspired multiscale flow-fields for water management and performance enhancement in proton exchange membrane fuel cells (PEMFCs). A fully coupled three-dimensional multiphase CFD model is developed to investigate the interaction between reactant transport, liquid water distribution, and pressure dynamics under varying operating conditions. The results show that the bio-inspired multiscale architecture significantly improves transport behaviour by enhancing reactant redistribution and promoting capillary-assisted water removal. Field-resolved analysis indicates that the proposed design reduces average liquid water saturation by approximately 28–35% and improves oxygen distribution uniformity by up to 22%, leading to an increase in net power density of 14–18% while maintaining controlled pressure-drop characteristics. Parametric sensitivity analysis further identifies an optimal design region characterized by moderate branching ratio, controlled branching angle, and balanced hierarchical depth, which together provide an effective trade-off between transport enhancement and hydraulic efficiency. In addition, time-resolved analysis and performance–pressure trade-off evaluation confirm that the proposed architecture operates within a favourable regime under dynamic conditions without incurring excessive parasitic losses. Overall, the findings demonstrate that bio-inspired multiscale flow-field design offers a physically grounded and scalable strategy for improving both performance and operational stability in PEMFC systems.