MODELING ARTIFICIAL SECONDARY INSTABILITY OF THIN WAVY GAS-SHEARED LIQUID FILM

Abstract

The surface of a liquid film under strong gas shear is covered by waves of different types and scales, interacting with each other. This is true for film flows both with and without liquid entrainment. The most common type of such interaction is the generation of slow short-living waves at the rear slopes of fast large-amplitude long-living waves. These waves are referred to as ‘secondary’ and ‘primary’, respectively. In the present work, we model the process of generation of secondary waves due to strong localized agitation of film surface at different locations with respect to the phase of primary waves. In real flow, such events are expected to occur due to large-scale turbulent pulsations in the gas phase. It was found that for stabilized flow with stationary nonlinear waves, the inception of such perturbation leads to the formation and growth of a secondary wave with spatiotemporal behavior similar to that observed in the experiments. This is true for the base film and the lower half of the rear slope of a primary wave. At the crest and front parts of primary waves, the perturbations decay quickly. The same regularities are observed in the experiments.