Control of Surface Tension Flows: Instability of a Liquid Jet

Abstract

A technique of controlling surface tension flows using thermal radiation is proposed. This method takes advantage of the dependence on temperature of the surface tension forces to produce the desired controlling effects. In this research, a capillary water jet is taken as an example of a surface tension dominated flow. The ability to cancel a preexisting unstable perturbation is demonstrated. First an acoustical disturbance that dominates the naturally occurring perturbations is applied to the jet. This causes jet breakup at a shorter and constant distance from the orifice. Next, a CO2 laser beam, modulated at the same frequency as the primary disturbance, is focused on the surface of the jet. By proper adjustment of intensity and phase the two perturbations cancel each other and the natural breakup of the jet is recovered. The influences of phase and intensity mismatches were tested and are reported. In addition to its application to delaying breakup of capillary jets, this technique is a promising method of controlling both suface tension driven flows and instabilities in different industrial applications.