The unsteady global dynamics of a gravitational liquid sheet interacting with a onesided adjacent air enclosure, typically referred to as nappe oscillation, is addressed, under the assumptions of potential flow and presence of surface tension effects. Preliminary physical insights of the sheet centerline sinuous modes show that the nappe dynamics features the propagation of two wave fronts both directed downstream or one downstream and the other one upstream depending on whether the flow Weber number is greater or less than unity, respectively; moreover, the overall system behaves as a driven damped spring-mass oscillator, where the liquid sheet acts as the mass and the air enclosure as the spring. The findings of the eigenvalues spectral analysis closely agree with direct numerical simulations of the partial differential equation governing in the space-time domain the global evolution of the disturbances, starting from an initial gaussian-like shape. Keywords: liquid sheet, surface tension, numerical visualization
Numerical visualization of nappe oscillation / Girfoglio, Michele; DE ROSA, Fortunato; Coppola, Gennaro; DE LUCA, Luigi. - (2015), pp. 1-10. (Intervento presentato al convegno 10th Pacific Symposium on Flow Visualization and Image Processing tenutosi a Naples nel 15-18 june 2015).
Numerical visualization of nappe oscillation
DE ROSA, FORTUNATO;COPPOLA, GENNARO;DE LUCA, LUIGI
2015
Abstract
The unsteady global dynamics of a gravitational liquid sheet interacting with a onesided adjacent air enclosure, typically referred to as nappe oscillation, is addressed, under the assumptions of potential flow and presence of surface tension effects. Preliminary physical insights of the sheet centerline sinuous modes show that the nappe dynamics features the propagation of two wave fronts both directed downstream or one downstream and the other one upstream depending on whether the flow Weber number is greater or less than unity, respectively; moreover, the overall system behaves as a driven damped spring-mass oscillator, where the liquid sheet acts as the mass and the air enclosure as the spring. The findings of the eigenvalues spectral analysis closely agree with direct numerical simulations of the partial differential equation governing in the space-time domain the global evolution of the disturbances, starting from an initial gaussian-like shape. Keywords: liquid sheet, surface tension, numerical visualizationI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
