Asymmetric coalescence-induced droplet jumping on hydrophobic fibers. (29th June 2019)

• Record Type: Journal Article
• Authors: Li, Bingbing; Xin, Feng; Zhu, Guorui; Tan, Wei
• Is Part Of: Chemical engineering science. Volume 201(2019)
• Page Start: 298
• Page End: 308
• Publication Date: 2019-06-29
• Subjects: Asymmetric coalescence -- Theoretical model -- Hydrophobic fiber -- Capillary-inertial scaling law -- Critical jumping radius ratio; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2019.02.041
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: A model for asymmetric coalescence of droplets jumping on fiber was established. Capillary-inertial scaling law of merged droplet jumping on fiber was researched. Jumping critical radius ratio for droplet on fiber was determined by the model. Abstract: Coalescence of two unequal-sized droplets on hydrophobic fibers is more common in nature. To elucidate the mechanism of merged droplets jumping on hydrophobic fibers, a new theoretical model for two unequal-sized droplets coalescence was first developed, which considered the effects of contact angle hysteresis and droplet-fiber contact area. Then, the influences of Ohnesorge number ( Oh ), droplet radius ratio ( n ), droplet-fiber radius ratio ( k ) and contact angle (CA) on the dimensionless jumping velocity ( U / vci ) were studied theoretically. The value of U / vci increased with the increase of n, k and CA but decreased as Oh increased. The dimensionless jumping velocity for two unequal-sized droplets coalescence on hydrophobic fibers still followed the capillary-inertial scaling law with U / vci ≈ 0.45 when n = 0.5. In addition, the effects of k and CA on the critical jumping radius ratio were the critical jumping radius ratio being reduced as k and CA increased, and the minimal critical jumping radius ratio was approximately 0.1. These findings will help to characterize coalescence-induced droplet jumping on hydrophobic fibers.