Wind turbine blades are generally made with glass fibers that are impregnated with epoxy or unsaturated polyester resins. They consist of 3 main components that are manufactured by a vacuum-assisted resin infusion (VARI) process: the blade spars which are usually thick monolithic laminates consisting of unidirectional layers, and the skins and shear panels which are manufactured as sandwich plates, with a polymer or balsa core. To avoid the appearance of manufacturing defects during the infusion of these components, it is necessary to master the manufacturing process and optimize its parameters. However, the VARI process is difficult to optimize for wind turbine blades because the current simulation tools don’t accurately reproduce its details for such large parts. Indeed, several aspects of the process are not yet integrated into the simulations, such as the decompaction of the fibrous reinforcement during the flow and the role played by the high permeability medium placed above the reinforcement to accelerate the infusion. The sandwich structure of the shear panels and skins also complicates the simulation procedure. In addition, computing times quickly become excessive when it comes to large scale infusion simulations. This paper proposes a simplified and robust procedure to simulate the infusion process for wind turbine blades. First, a method of characterizing the equivalent permeability for infusion processes is adapted to infusion with distribution medium and the PAM-RTM software is used to develop simplified numerical simulations of reinforcement filling with finite "shell" elements. Moreover, the effects of the reinforcement decompaction is integrated into the simulations of the filling. Finally, the effects of temperature variation in non-isothermal simulations including both reinforcement filling and composite curing are considered.