Regularized thin-fiber model for nanofiber formation by centrifugal spinning.

: We propose a regularized thin-fiber (string) model that overcomes past numerical limitations and allows determination of the steady fiber velocity and diameter of a semi-infinite Newtonian viscous fiber emerging from a nozzle rotating about an axis in the presence of centrifugal, inertial, and viscous forces of arbitrary magnitudes. The results are controlled by two dimensionless groups, namely, the Rossby number Rb expressing the ratio of inertial to centrifugal forces and the Reynolds number Re, the ratio of inertial to viscous forces. We find that for Rb 0.5, regularization is not required, the curvature in fiber trajectory is increased by viscosity, and the solution at large distances along the spin line does not converge to the inviscid result. Regimes of behavior in the plane formed by Re and Rb are mapped out and example behavior is given for each regime.