Emerging from the advances in both manufacturing and computational modelling techniques, it is possible to investigate the performance of an ordered microstructure manufactured by high resolution additive manufacturing processes. In a previous study, we have investigated the direct simulation of effective transport properties [1] and within this work, two-phase flow dynamics coupled with the appropriate boundary conditions present in an operating fuel cell (microporous layer defects and gas channel coupling) on an idealised carbon paper and ordered lattice microstructures.OpenFOAM was used to simulate two-phase flow in the void space of both the porous structures and gas channels coupled with the Volume of Fluid (VoF) method in 2D and 3D simulations. The effective electrical conductivity and permeability was determined for each structure for comparison. To more accurately envisage the replacement of traditional materials with the new conceptual material, more accurate boundary conditions were investigated, including injection from an imposed micro-porous layer defect which was extracted from an SEM image shown in Figure 1. Additionally, coupling the dynamic effects of the gas channel on the fluids within the porous domains allowed for additional insight to the stability of the two-phase flow.Pore-scale simulations illustrate that only certain ordered structures will promote beneficial two-phase flow in fuel cells in terms of reducing the amount of flooding and oxygen diffusional resistance. Alternatively, it has been shown that the ordered microstructures improve both electrical conductivity and permeability if they can be made from the same carbon material. The ordering of structures to be used as new micro and nano materials is a new area of investigation, which would provide further evidence of performance improvements due to structures.Furthermore, the dynamic two-phase flow effects on local clusters of water have been investigated and analyses to show how both the gas channels supplying oxygen and microporous layer defects can significantly affect the fluid dynamics including; droplet growth, detachment and transport within the gas channels. This work and its findings was validated by the comparison of the VoF method to mCT data for water injection through a standard GDL and with growth and detachment in the channel. The results showed good agreement between the interface dynamics, location and shape.[1] D. Niblett, V. Joekar-Niasar, and S. Holmes, “Optimisation of Fuel Cell Gas Diffusion Layers using Ordered Microstructural Design,” Journal of The Electrochemical Society, vol. 167, no. 7, p. 013520, 2018.Figure 1 - Simulation of water injection into reconstructed ordered and carbon paper microstructures to evaluate the performance of the materials in management of water. Figure 1