Resin Infusion (RI) process is frequently used for large composite parts production. This Liquid Composite Molding method uses vacuum pressure to shape a plastic bag as a counter mold. Once a complete vacuum is achieved, the resin is sucked into a dry preform textile laminate via placed tubing. In this note we introduce a 2.5D model for a Liquid Composite Molding LCM process starting from a recent one introduced by Besson and Poussin in Besson and Pousin (2005) for the Resin Transfer Molding RTM process. Moreover for 2.5D models defined over quadrilateral reference domains, we show the effectiveness of the use of the Proper Generalized Decomposition. Finally, we propose a procedure, for a particular class of 2.5D model, in order to perform a numerical simulation of a mold filling process.