Résumé
Resin Transfer Moulding is a widely used process in composite material manufacturing, involving the compaction of a fibrous 3D interlock preform to reach the desired Fibre Volume Fraction (FVF), followed by impregnation with liquid polymer resin. Understanding the dual-scale flows of resin within and between homogeneous equivalent porous yarns is essential for predicting impregnation defects. At the mesoscopic scale, fabric unit cells are characterised by yarn morphology and intra-yarn FVF fields, converted into a permeability tensor field via Darcy’s law. This dual-scale nature significantly affects saturated and unsaturated fluid flows, especially due to capillary phenomena within yarns, modelled by a capillary pressure. The aim is to develop a robust numerical framework for simulating fibrous media impregnation at the mesoscopic scale. Fluid flow is modelled by Darcy'sequation within porous yarns and by Stokes' equation between yarns, employing a monolithic approach with a mixed velocity-pressure formulation stabilised by a VMS method. Accurate description of resin flow within porous yarns requires locally oriented intra-yarn permeability tensor fields and capillary stress tensor at the resin-air interface. Additionally, pressure enrichment is introduced at the fluid front, represented by a level set function, to capture pressure discontinuity in Darcy domains. Saturated and unsaturated Stokes-Darcy fluid flow simulations are conducted to determine fabric permeability as a function of global FVF at different compactions and to evaluate the influence of capillary phenomena on the impregnation scenario.