We investigate the linear stability of a flat interface that separates aliquid layer from a fully-developed turbulent gas flow. In this context,linear-stability analysis involves the study of the dynamics of asmall-amplitude wave on the interface, and we develop a model that describeswave-induced perturbation turbulent stresses (PTS). We demonstrate the effectof the PTS on the stability properties of the system in two cases: for alaminar thin film, and for deep-water waves. In the first case, we find thatthe PTS have little effect on the growth rate of the waves, although they doaffect the structure of the perturbation velocities. In the second case, thePTS enhance the maximum growth rate, although the overall shape of thedispersion curve is unchanged. Again, the PTS modify the structure of thevelocity field, especially at longer wavelengths. Finally, we demonstrate akind of parameter tuning that enables the production of the thin-film (slow)waves in a deep-water setting.
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