Three-dimensional wave distortion and disintegration of thin planar liquidsheets

Three-dimensional dilational and sinuous wave propagation on infinite or se miinfinite thin planar sheets flowing into a gas of negligible density is i nvestigated. The assumption of thin sheets allows the reduction of the prob lem dimensionality by integration across the sheet thickness. For finite-am plitude disturbances, the strongest nonlinear effects occur when the cross- sectional wavenumber (l) is close to the streamwise wavenumber (k). First, dilational wave propagation is considered. When I is close to Ii for infini te sheets, higher harmonics are generated in the streamwise direction, and the standing wave with finite amplitude in the cross-sectional plane become s flat. As time passes, the waves return to the initial wave shape. This pr ocess is repeated in a cycle. A similar phenomenon is found in semi-infinit e sheets with low Weber number. When I is close to Ii for semi-infinite she ets and Weber number is high, fluid accumulates into fluid lumps interspace d by one wavelength in the cross-sectional direction as well as in the stre amwise direction. This leads to the formation of initially non-spherical li gaments or large droplets from the liquid sheet. Secondly, sinuous wave pro pagation is considered. When I is close to k for semi-infinite sheets and W eber number is high, fluid agglomerates in the edge of the sheet interspace d by half a wavelength ill the cross-sectional direction as well as in the streamwise direction. A three-dimensional visualization of the computationa l results shows that the disturbance at the nozzle exit induces fluid to ag glomerate into half-spherical lumps, which indicate the formation of ligame nts or large droplets from the liquid sheet. A similar phenomenon is found in the case of infinite sheets.