An authenticated theoretical modeling of electrified fluid jet in core--shell nanofibers production

extcopyright 2017, extcopyright The Author(s) 2017. Control and optimization of coaxial electrospinning process is a serious concern due to its multiparameter effectiveness. This study is concerned with modeling and simulation of process by solving the governing equations of electrified jet using FEniCS software packages applying Cahn--Hilliard and Newton solvers for finite element method. Jet diameter, solvent evaporation, electrical field, and velocity changes are focused in this model as the most effective parameters on final nanostructures quality. An experimental core--shell nanofiber production (polyvinyl alcohol) in the same spinning condition with simulated spinning is applied to validate the model. Both theoretical and experimental results demonstrate that core and shell diameter increases by increase in nozzle diameter and polymer solution concentration. Relative error shows that for the higher nozzle diameter, the model can have an acceptable prediction for final diameter which is more accurate for shell diameter part. The simulation results for jet velocity indicate a sharp sinusoidal increase during jet motion. Electric field simulation also shows a result similar to Feng's model with an increase near the nozzle and a very slow decline at the end which both are confirmed by other experimental and numerical studies. It is also concluded that by enlargement of nozzle diameter, solvent evaporation takes more time and as a result, the inhomogeneity and diameter increase which have the same trend as experimental results. The relative error of evaporation time decreases in nanojets with higher diameter. And the model has an acceptable compatibility with experimental results especially for nozzle diameters more than 50 µm.