Using computational fluid dynamics to study the effect of contact angle on microdroplet deformation

G. Rosengarten, D. Harvie, J. Cooper--White


Computational fluid dynamics (?) is used to study the effect of contact angle on droplet shape as it moves through a contraction. A new non-dimensional number is proposed in order to predict situations where the deformed droplet will form a slug in the contraction and thus interact with the channel wall. We argue that droplet flow into a contraction is a useful method to ensure that a droplet will wet a channel surface without a trapped lubrication film. We demonstrate that when a droplet is larger than a contraction, capillary and Reynolds numbers, and fluid properties may not be sufficient to fully describe the droplet dynamics through a contraction. We show that with everything else constant droplet shape and breakup can be controlled simply by changing the wetting properties of the channel wall. ? simulations with contact angles ranging from 30 ? to 150 ? shows that lower contact angles can induce droplet breakup while higher contact angles form contact-angle dependent shape slugs.

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ANZIAM Journal, ISSN 1446-8735, copyright Australian Mathematical Society.