A fully nonlinear model for atomization of high-speed jets

A nonlinear model has been developed to assess the time-dependent evolution of an axisymmetric liquid jet using a boundary element method. Vorticity transported from the boundary layer in the orifice passage to the free surface is modeled using a potential ring vortex placed at the orifice exit plane. The vortex strength is uniquely determined using information from Kutta condition and information regarding the boundary layer thickness at the orifice exit plane. It is shown that the primary breakup can occur even without the presence of the gas phase. Using a secondary stability analysis after Ponstein's [8], the size of droplets is estimated based on the size of the ring-type structures shed from the periphery of the jet. Computed droplet sizes are in reasonable agreement with experimental data although turbulence effects obscure some comparisons.