Multiscale simulation of liquid jet disintegration and primary atomization using Eulerian-Lagrangian coupling

A multiscale approach for the numerical simulation of liquid jet disintegration and primary atomization is investigated using an Eulerian-Lagrangian coupling. In this approach, a numerical simulation using volume of fluid method (VOF) is carried out to model the global (meso-scale) spreading of liquid jet. The formation of the micro-scale droplets, which are usually smaller than the grid spacing in computational domain, is determined by a surface energy-based sub-grid model. Where the disruptive forces (turbulence and surface pressure) of turbulent eddy near the surface of the jet overcome the consolidating surface tension, Lagrangian droplets are released with the local properties of corresponding eddies. The dynamics of generated droplets are modelled using Lagrangian particle tracking (LPT). A numerical coupling between Eulerian and Lagrangian frames is then established via mass, momentum and volume of fluid source terms. The presented methodology was tested for different liquid jets in Rayleigh, wind-induced and atomization regimes and validated against literature data. The droplet size distributions and Sauter mean diameter (SMD) values from numerical simulations are in good agreement with experimental correlations.