Electrified jet

As for the formation of ultrathin fibers, it is hypothesized that repulsion between surface charges causes the electrified jet to splay or split into many small fibers of approximately equal diameter and charge per unit length, and the final diameter of the electrospun fibers upon collection is dependent upon how many splays are... 

In the context of the electrified jets in electrospraying and electrospinning, the distributed force q originates from the Coulomb repulsion of different parts of the jet surface. Then, it is given by the following expression [9-11]... 

The electrified jets of concentrated polymer solutions move in air with low speeds of the order of 1 m/s. However, they bend due to the Coulombic interactions discussed above in relation with the electric bending force (2.20). Such jets emerge... 

Fig. 2.8 Illustration of the instability, leading to bending of an electrified jet (After [9]. Courtesy of AIP)...

Abstract This chapter reviews atomization modeling works that utilize boundary element methods (BEMs) to compute the transient surface evolution in capillary flows. The BEM, or boundary integral method, represents a class of schemes that incorporate a mesh that is only located on the boundaries of the domain and hence are attractive for free surface problems. Because both primary and secondary atomization phenomena are considered in many free surface problems, BEM is suitable to describe their physical processes and fundamental instabilities. Basic formulations of the BEM are outlined and their application to both low- and highspeed plain jets is presented. Other applications include the aerodynamic breakup of a drop, the pinch-off of an electrified jet, and the breakup of a drop colliding into a wall. 

Keywords Bond number Boundary element method Drop impact Electrified jet Liquid jet Pinch-off Primary and secondary atomization... 

Rayleigh-Taylor. Also, BEM modeling of the secondary breakup of a primarily atomized droplet is briefly reviewed. Furthermore, the BEM modeling of atomization processes of electrified jets is discussed. The BEM modeling for a snap-off or atomization of the rising liquid rim from the drop impact phenomenon, known as the crown, is also discussed. 

BEM can be extended to compute interior fluxes by taking the derivative of the velocity potential from the governing equation (18.4). Yoon et al. [3] computed the interior fluxes of the electrostatic field outside an electrified jet whose symmetric sector configuration is shown in Fig. 18.14. Assuming symmetry, they computed a sector of the multi-jets, which can produce extremely small (a few or sub-micron) droplets. The multi-jet mode enables multiple cone-jet operation (about 5 10 jets), which in turn increases the flow rate without sacrificing basic features of the eletrospray s cone-jet mode [82]. 

Fig. 32.10 The picture on the left shows varicose instabilities of an electrified jet (Reprinted with permission [17]). The picture in the center and on the right show the cone-jet mode of electrospray operation in an electrospray system in our lab. Experiment conditions 3,200 V applied at emitter orifice, 11.5 jL/min flow rate of 90% aqueous methanol, 10 irun ground distance from emitter...

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