The Nomenclature of the Variables
$\rho$	The density of the liquid
$\gamma$	The surface tension of the liquid
$d_n$	The nozzle outer diameter
$f$	The pulsation frequency of the jet ejection under constant applied voltage
${\epsilon }_0$	The dielectric constant of air
${\epsilon }_r$	The relative dielectric constant of the liquid
$\mu$	The viscosity of the liquid
$U$	The applied voltage
$H$	The nozzle-to-substrate distance
$V$	The ejection volume
$Q_e$	The equivalent flow rate on the jet
$E_n$	The normal electric field on the meniscus
$Q_s$	The supplied flow rate
$K$	The conductivity of the liquid
${\tau }_s$	The electric shear stress
$E_s$	The electric shear field
$\sigma$	The surface charge density
${\sigma }_e$	The equilibrium surface charge density
$I$	The current emitted by the jet
$r_c$	The diameter of some point at the cone surface
$d_j$	The jet diameter
$t_e={\epsilon }_r{\epsilon }_0/K$	The charge relaxation time
$t_c={(\rho d_n^3/\gamma )}^{1/2}$	The capillary time
$L_n$	The length of the nozzle
$U{}^{\prime }$	The dimensionless applied voltage
$V{}^{\prime }$	The dimensionless ejection volume
$K{}^{\prime }$	The dimensionless conductivity
$H{}^{\prime }$	The dimensionless nozzle-to-substrate distance