Transport and deposition of ellipsoidal fibers in low Reynolds number flows

Abstract

The motion of elongated, ellipsoidal fibers in low Reynolds number flows was studied using a computational modeling approach. The computer model resolved the coupled translational and rotational motion of fibers in laminar flows. The computational model was applied in a circular duct and the transport and deposition of ellipsoidal fibers with different sizes and aspect ratios were simulated. An experimental setup was also developed and deposition of glass fibers in a pipe flow in laminar flow regime was measured. A fiber classifier was used to generate fibers with different aspect ratios in controlled condition. The computational model predictions were compared with the experimental data and good agreement was observed. It was found that the flow shear rate, the fiber aspect ratio, and the particle-to-fluid density ratio significantly affect the transport and deposition of ellipsoidal fibers. It was also found that the computational model should account for the duct flow entrance region in order to provide physically realistic predictions. Attention was given to comparing the effectiveness of using equivalent spheres to approximate the elongated fibers. Several commonly used equivalent spheres were studied, and their suitability for characterizing motion of ellipsoidal fiber particles in the laminar flow was studied.