Power law liquid jets’ trajectories and instability during centrifugal spinning

Abstract

Nanofibers are produced using a revolutionary technique called centrifugal jet spinning. This technique is known as an industrial prilling process, where small droplets are performed from breaking up of a thread liquid jet. Therefore, It has been used the curved jet to control the size of these small droplets and the break-up length. In this study, the linear instability of a power law liquid jet is investigated in the presence of centrifugal forces, gravity and surface tension. Furthermore, an asymptotic method has been applied to simplify the system of governing equations into a set of one-dimensional equations. Therefore, the trajectory of the power law liquid jet during the centrifugal spinning has been determined using the Roung-Kutta method. Further investigation has been done into wavenumber and the growth rate of the most unstable mode for various flow index numbers. From the linear instability results, it can be observed that when the rotation rate and gravitational force are high, shear thickening is more stable than shear thinning jets. We have also found that more viscous becomes longer jets and it produces larger droplet which is a crucial finding.

Keywords

• Instability
• Centrifugal spinning
• non-Newtonian jets
• Gravity