Modeling multi-scale liquid dispersion phenomena in conjunction with Computational Fluid Dynamics
S. Mohan, A. Haidari and A. Mukopadhyay
Fluent, Inc., US
mono-disperse droplets, surfactant transport, elasticity, break-up, coalescence, surface tension
Mixing of fluid in different geometric scales dominates variety of real life applications ranging from engineering chemicals, food materials, pharmaceutical products to biological organs. In this presentation we will address coupling of continuum scales in a number of engineering applications viz., geometrically mediated breakup of drops in microfluidic devices, generation of mono-dispersed droplets with confluent laminar flows and droplet deformation due to surfactant migration at liquid-liquid interfaces. Within the framework of traditional CFD modeling, these applications need both resolution of appropriate scales and / or sub-grid-scale modeling of criteria for interface formation including dynamics such as break-up and coalescence. Additionally they involve heterogeneous species transfer across the interface. In the first example, droplet break-up in microfluidic devices is shown to be a function of extension and capillary numbers. The accuracy in predicting the formation of the daughter droplets is demonstrated. In the second example, role of hydrophobic behavior of the fluids in creation of mono-dispersed droplets in water-oil systems is identified. The last example illustrates the dynamic variation of surface tension by resolving the surfactant concentration distribution between the droplet bulk and the interface. The modified surface tension distribution causes the deformation of the dispersed phase.
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Nanotech 2006 Conference Program Abstract