Viscous effects in droplet-ejecting capillary waves

Surface waves produced by parametric excitation experience a transition between simply connected waves and droplet-ejecting waves when the applied 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 frequency while high viscosity fluids have thresholds which depend on only viscosity and forcing frequency. Models for the transition based on the condition that the wavelength, waveheight ratio approaches a fixed value at the transition are consistent with our observations.