MECHANISM OF ATOMIZATION OF A LIQUID JET

A linear stability analysis is presented for a viscous liquid jet in an inviscid gas medium, with three dimensional disturbances. Although Squire's theorem is applicable for an inviscid jet, it is not valid for the present case of a cylindrical viscous liquid jet. It is found that three-dimensional waves are relatively unimportant at low Weber numbers, but their growth rate becomes almost identical to that of varicose waves at large Weber numbers. Thus three-dimensional waves become observable at large Weber numbers. In particular, sinuous waves can become the most unstable waves under certain flow conditions within the wind-induced breakup regime. As the Weber number is increased, more and more three-dimensional disturbances become unstable and significant, and hence the jet breakup process becomes more and more complicated. These results agree well with experimental observations. Further, the results suggest the existence of the vanishingly small liquid jet breakup length, thus explaining why in the atomization regime the liquid jet disintegrates almost immediately at the nozzle exit.