Phase Separation of Two-Fluid Mixtures using Surface Acoustic Waves:Developing Basic Principles in a Quest for Enhanced Water Recovery

The phase separation of multi—phase systems and in particular of oil—water mixtures is of significance for water recovery. We focus on experimental, theoretical, and computational exploration of basic physical mechanisms involved in phase separation in a recently discovered acoustic—flow phenomena. The mechanism is based on application of surface acoustic waves (SAWS), which propagate in a solid substrate in contact with oil—water mixtures, which usually contain surface active molecules such as in soap to stabilize the mixture. In particular, sound wave leakage off the SAW and a carefully designed substrate wettability push emulsion droplets in the mixture away from the solid substrate, which yield two fluid phases of oil and water, one close to the substrate and the other far from the substrate. In addition, An acoustowetting effect further supports the separation of the two fluid phases by discriminating over their wetting properties, extracting just one of the phases outside of the original mixture. Altogether the different mechanisms yield the phase separation of oil and water mixtures to a separate oil and water phases. In parallel, we will work on developing a theoretical model for the physics of phase separation in the experiment. The theory and computations will guide the experiment and will give insight into the physical mechanisms governing the phase separation process. This work will lead to the establishment of proof—of—principle for the use of SAWS for the purpose of phase separation.