Experimental Characterization of Optically-Actuated Surface Waves on a Parametrically-Forced Fluid Interface

If a free fluid interface is subjected to sufficiently strong vertical oscillations, it spontaneously becomes unstable and gives way to so-called Faraday waves. Below this threshold, the interace remains flat and is stable to perturbations. However, if the strength of the vertical forcing is close to but below the Faraday threshold, perturbations of the interface can lead to relatively long-lived, if transient, surface waves. In this talk, we present a preliminary experimental characterization of surface waves generated when an infrared laser is pulsed on the surface of a parametrically-forced silicone oil bath. The wave topography is characterized using free-surface synthetic schlieren and compared to wave fields generated when a millimetric drop bounces on the interface. The effect of the phase between the laser pulses and the vertical driving on the actuation and subsequent evolution of surface waves is discussed.