Dynamic ordering caused by a source-sink relation between two droplets. Issue 34 (22nd August 2022)

• Record Type: Journal Article
• Authors: Watanabe, Chiho; Tanaka, Shinpei; Löffler, Richard J. G.; Hanczyc, Martin M.; Górecki, Jerzy
• Is Part Of: Soft matter. Volume 18:Issue 34(2022)
• Page Start: 6465
• Page End: 6474
• Publication Date: 2022-08-22
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/d2sm00497f
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Complex modes of synchronized motion in a system of 1-decanol and paraffin droplets at different concentrations of Sudan Black B dye. Abstract : Two droplets composed of different chemicals, 1-decanol and liquid paraffin, floating on the water surface show characteristic co-responsive behavior. The presence of two different types of droplets in the system imposes an asymmetry that would not be possible with single droplets alone. The self-propulsion and interactions between droplets appear because surface active 1-decanol molecules provided by the source are absorbed by the paraffin sink thus generating an asymmetric surface tension gradient. This source-sink relation between droplets stabilizes and enhances the self-propulsion, and leads to a variety of dynamic structures including oscillations in the inter-droplet distance. We found that the character of time evolution also depends on the concentration of dye, Sudan Black B, initially used just to stain the decanol droplet. A simple mathematical model explains the transition between the stationary state and the oscillations as a Hopf bifurcation.