(353e) Multiphase Flow of Miscible Liquids: Jets and Drops

Drops and jets of liquids that are miscible with the surrounding bulk liquid are present in many processes from cleaning surfaces with the aid of liquid soaps to the creation of biocompatible implants for drug delivery.  Although the interactions of immiscible drops and jets show similarities to miscible systems, the small, transient interfacial tension associated with miscible systems create distinct outcomes such as intricate droplet shapes, break-up resistant jets, and spreading sessile drops.

Experiments and simulations have been conducted to understand several basic multiphase flow problems involving miscible liquids.  Direct comparisons for the free-surface pendant drops resulting from drop impaction and for the dissolution of sessile drops in a miscible bath have been completed.  Using high-speed imaging of the morphological evolution of the flows and finite element analysis to solve the coupled Navier-Stoke/Cahn-Hilliard model using diffuse-interface theory, we have been able to show that these processes are controlled by interfacial tensions.  Since the measurements of the surface stresses in a miscible system are difficult to measure, the ability to match simulations to the experimental results allows a deeper understanding of the evolution of the apparent interfacial energy of the system.

Further multiphase flows include investigating miscible jets, which allow the creation of fibers and tubular shapes from inelastic materials that are otherwise difficult to process due to capillary breakup.  This work shows that stabilization from the diminishing interfacial tensions of the miscible jets allow various elongated morphologies to be formed.  When combined with a mechanism to freeze these fibers, highly oriented materials, such as anisotropic collagen fibers used as scaffolds for regeneration of anisotropic tissues, can be created.