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|Title: ||Non-coalescence of oppositely charged drops|
|Authors: ||Ristenpart, W. D.|
Bird, J. C.
Stone, H. A.
|Keywords: ||electric field|
|Issue Date: ||17-Sep-2009|
|Citation: ||Nature 461, 377-380 (2009)|
|Abstract: ||Oppositely charged drops have long been assumed to experience an attractive force that favors their coalescence. Here we demonstrate the existence of a critical field strength above which oppositely charged drops do not coalesce. We observe that appropriately positioned and oppositely charged drops migrate towards one another in an applied electric field; but whereas the drops coalesce as expected at low field strengths, they are repelled from one another after contact at higher field strengths. Qualitatively, the drops appear
to ‘bounce’ off one another. We directly image the transient formation of a meniscus bridge between the bouncing drops, and propose that this temporary bridge is unstable with respect to capillary
pressure when it forms in an electric field exceeding a critical strength. The observation of oppositely charged drops bouncing rather than coalescing in strong electric fields should affect our
understanding of any process involving charged liquid drops, including de-emulsification, electrospray ionization and atmospheric conduction.|
|Appears in Collections:||Fluid Dynamics Videos|
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