Joseph Paulsen: 0000-0001-6048-456X
airflow, bubble, coalescence, data acquisition, fluid flow, microscopy, viscocity, droplet collision
We thank Osman Basaran, Efi Efrati and Wendy Zhang for many enlightening discussions. We thank Irmgard Bischofberger and Andrzej Latka for measurements of fluid parameters of the silicone oils used. J.D.P. gratefully acknowledges a Grainger Foundation Fellowship. This work was supported by NSF Grant DMR-1105145, NSF-MRSEC DMR-0820054 and NSF-PREM DMR-0934192.
When two liquid drops touch, a microscopic connecting liquid bridge forms and rapidly grows as the two drops merge into one. Whereas coalescence has been thoroughly studied when drops coalesce in vacuum or air, many important situations involve coalescence in a dense surrounding fluid, such as oil coalescence in brine. Here we study the merging of gas bubbles and liquid drops in an external fluid. Our data indicate that the flows occur over much larger length scales in the outer fluid than inside the drops themselves. Thus, we find that the asymptotic early regime is always dominated by the viscosity of the drops, independent of the external fluid. A phase diagram showing the crossovers into the different possible late-time dynamics identifies a dimensionless number that signifies when the external viscosity can be important.
Coalescence of bubbles and drops in an outer fluid. JD Paulsen, R Carmigniani, A Kannan, JC Burton, & SR Nagel, Nature Communications 5, 3182 (2014).
Coalescence of bubbles and drops in an outer fluid. JD Paulsen, R Carmigniani, A Kannan, JC Burton, & SR Nagel, Nature Communications 5, 3182 (2014)
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