A Numerical Model for Simulating the Motions of Ellipsoidal Fibers Suspended in Low Reynolds Number Shear Flows

摘要

A computational model was developed to simulate the motions of ellipsoidal fibers suspended in viscous shear flows. The model incorporates drag, lift, gravity, and hydrodynamic torque acting on ellipsoidal particles. Two numerical experiments were conducted to test the accuracy of the model. First, a single fiber was subjected to a linear shear profile and allowed to rotate without translation. The model's predictions for the fiber rotational period were evaluated and were shown to match well with previously published theoretical and numerical values. Second, fibers were injected into a horizontal tube under different flow conditions and their motions were tracked. Inspection of individual fiber motion showed a tendency to remain aligned with the direction of bulk fluid flow. Fiber aspect ratio, injection location, and flow rate were shown to play important roles in the details of elongated particle motions. The predicted sedimentation efficiencies of fibers matched well with the previously published works. On the basis of the computational model results, an empirical expression for the sedimentation rate of fibers in a horizontal tube with circular cross-section was proposed.