The influence of fiber orientation and mold geometry variations on the reactive polymerization of epsilon-caprolactam during the mold filling phase in reactive processing is depicted in this work with the help of Computational Fluid Dynamics (CFD). Therefore the established Malkin kinetics is employed to describe the polymerization process combined with a model that correlates the viscosity of the reactive mixture with the local polymer conversion. To account for the reinforcing textile elements used for production of lightweight parts and the corresponding effects on the injection process, an approach is presented to correctly depict arbitrary fiber orientations within the cavity. Application of these models in CFD enables us to simulate the injection process for complex geometries and varying fiber orientations. Main focus lies on the identification of variations of the How patterns and local alterations of the polymer conversion induced by different geometry elements and fiber orientations at otherwise constant production parameters. (C) 2015 Elsevier Ltd. All rights reserved.