VISCOUS EFFECTS IN DROPLET-EJECTING CAPILLARY WAVES

Surface waves produced by parametric excitation experience a transitio n between simply connected waves and droplet-ejecting waves when the a pplied forcing exceeds a threshold level. Our measurements on a number of different fluids indicate that low-viscosity fluids have threshold accelerations which depend on only surface tension and forcing freque ncy while high viscosity fluids have thresholds which depend on only v iscosity and forcing frequency. Models far the transition based on the condition that the wavelength, waveheight ratio approaches a fixed va lue at the transition are consistent with our observations.