In the manufacturing process of large geometrically complex components comprising of fiber-reinforced composite materials by Resin Transfer Molding (RTM), the process involves injection of resin into a mold cavity filled with porous fiber preforms. The overall success of the RTM manufacturing process depends on the complete impregnation of the fiber mat by the polymer resin, prevention of polymer gelation during filling, and subsequent avoidance of dry spots. Since a cold resin is injected into a hot mold, the associated physics encompasses a moving boundary value problem in conjunction with the multi-disciplinary study of flow/thermal and cure inside the mold cavity. Although experimental validations are indispensable, routine manufacture of large complex structural geometries can only be enhanced via computational simulations, thus eliminating costly trial runs and helping the designer in the set-up of the manufacturing process. This study describes the developments towards formulating an effective simulation based design methodology using the finite element method. The specific application is for thin shell-like geometries with thickness being much smaller than the other dimensions of the part. Due to the highly advective nature of the non-isothermal conditions involving thermal and polymerization reactions, special computational considerations and stabilization techniques are also proposed. Validations and comparisons with experimental results are presented whenever available.