Extraordinarily Rapid Rise of Tiny Bubbles Sliding beneath Superhydrophobic Surfaces

Cyuan Jhang Wu, Cheng Chung Chang, Yu Jane Sheng, Heng Kwong Tsao

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Tiny bubbles readily stick onto substrates owing to contact angle hysteresis (CAH). Nevertheless, they can slide slowly on a tilted surface with ultralow CAH because capillarity is overcome by buoyancy. It is surprising to observe experimentally that bubbles of 3-15 µL (diameter 1.79-3.06 mm) slide beneath a tilted superhydrophobic surface at a vertical ascent rate faster than that of freely rising ones of high Reynold numbers ˜O(102). As the tilting angle increases, the drag coefficient remains essentially the same as that of a freely rising bubble, but the frontal area of the flat bubble rises monotonically. Nonetheless, the frontal area of the sliding bubble always stays much smaller than that of a freely rising bubble. Consequently, the small drag force associated with the sliding bubbles is attributed to their substantially small frontal areas on superhydrophobic surfaces.

Original languageEnglish
Pages (from-to)1326-1331
Number of pages6
JournalLangmuir
Volume33
Issue number5
DOIs
StatePublished - 7 Feb 2017

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