The advance in computational fluid dynamics in recent years has provided the opportunity for many fluid dynamic problems to be analyzed numerically. One such problem concerns the modeling of plunging water into a still water body, often encountered in pump stations. Air bubbles introduced into the system by the plunging jet can be a significant problem, especially when consumed into operating pumps. The classical approach to investigate the hydrodynamics of plunging jet in pump stations is by physical model studies. This approach is time consuming, tedious and costly. The availability of computational power today, along with appropriate numerical techniques, allows such phenomenon to be studied in a greater level of detail and more cost efficient. Despite the advantages of numerical studies, little attention has been devoted to solve the plunging jet and air transport problem numerically. In this current work, a 3-dimensional finite volume, Large Eddy Simulation (LES) code is developed to simulate these flow conditions. For turbulent flow, the large scale quantities were numerically resolved while the dynamic sub-grid scale model is used to model the small scale energy dissipations. The code also has the capability to handle free surface deformation, an important aspect in simulating the impact section of an impinging jet. Modeling of the air entrainment is performed numerically utilizing the information obtained from the hydrodynamics. Migration of air bubbles is modeled using the scalar transport equation, modified to account for the buoyancy of the bubbles. Instead of the typical Lagrangian schemes, which track individual air bubbles, air bubble dynamics are modeled in the form of concentrations. Modeling air bubbles in this manner is computational efficient and simpler to implement. For the air entrainment simulations, standard numerical boundaries conditions and empirical entrainment equations are used to provide the necessary boundary conditions. The developed model is compared with the literature, producing satisfactory results, suggesting that the code has an excellent potential of extending its application to practical industry practices.

Ce travail traite la problématique des bulles d’air contenues dans les pièces composites mises en œuvre par le procédé RTM. La modélisation des phénomènes de création, de compression et de transport de ce type de défauts est présentée. Notamment l’adoption d’un nouveau modèle de création des bulles d’air, de transport, et l’estimation des porosités à double échelle de pores ainsi que la saturation finale de la préforme sont données. / This work covers the problematic of air bubbles entrapped during manufacturing composite parts via the RTM process. Modeling creation, compression, and transport of this type of defaults is presented here. Likewise, a new approach of air bubble’s creation, transport modeling, simulation of porosities at dual scale of pores, and estimation of the final saturation of the preform are given.