On the Breakup of Viscous Liquid Sheets by Dual-Mode Linear Analysis

Abstract

The breakup of planeviscousliquid sheets moving in a gas stream hasbeen studied. Adual-modelinearstability analysis has been carried out under the combined ine uence of sinuous and varicose modes of disturbances at the two liquid‐gas interfaces. The effect of various parameters, such as the Reynolds number, Weber number, density ratio, velocity ratio, and the phase anglebetween thetwo modes, on the breakup characteristics of the liquid sheets has been investigated. At wavelengths corresponding to the dominant wavelengths for either the sinuous or the varicose mode, the breakup of the liquid sheet occurs at full-wavelength intervals, but the breakup point shifts between the half- and the full-wavelength when therespective dominant wavelengths corresponding to thesinuous and the varicose modes are applied simultaneously. The breakup time decreases as the proportion of the varicose mode is increased in the initial disturbance imposed on the liquid sheets. The breakup length (or time) decreases withanincreaseintheReynoldsnumber,Webernumber,densityratio,andvelocity ratio.Thesheetproe leschange for different values of Weber number, density ratio, velocity ratio, and the phase angle between the two modes. Comparison with experimental results shows that the present analysis is able to match the interface proe le close to the nozzle exit, but not further downstream where nonlinear effects are predominant.