Shear-induced migration of confined flexible fibers*

In this experimental study, we report the shear-induced migration of flexible fibers in suspensions confined between two parallel plates.

Non-Brownian fiber suspensions are placed and imaged in a rheo-microscopic set-up, where the top and the bottom plates counter-rotate and create a Couette flow.

Initially, the fibers are near the bottom plate due to sedimentation.

Under shear, the fibers move with the flow and migrate towards the center between the two walls.

Statistical properties of the fibers, such as the mean values of the positions, orientations, and end-to-end lengths of the fibers, are used to characterize the behaviors of the fibers.

The observation shows that more flexible fibers exhibit faster migration.

Different behaviors of the fibers are quantified with different flexibilities of the fibers, and the structures and the dynamics of the fibers are correlated with the migration.