Natural or artificial active objects can demonstrate mirror asymmetry of collective motion when they are moving coherently in a vortex. The majority of known cases related to the emergence of collective dynamical chirality are referred to as active objects with individual structure chirality and/or dynamical chirality. Here, we demonstrate that dynamically and structurally achiral active droplets can self-organize into vortex-like structures. Octane droplets dispersed in the aqueous solution of an anionic surfactant are activated with ammonia addition. The motion of droplets is due to the Marangoni flow emerging at the interfaces of the droplets. We found out that different modes of vortex motion of droplets in the emulsion can arise depending on the size of the region that confines the motion of the droplets and their number density and velocity.
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http://dx.doi.org/10.1021/acs.langmuir.1c01615 | DOI Listing |
ACS Nano
January 2025
Leibniz Institute of Polymer Research, Dresden 01069, Germany.
Droplet evaporation on solid substrates is a ubiquitous phenomenon and is relevant in many natural and industrial processes. Whereas it has been reported that the evaporation process is sped up on soft substrates compared with that on hard substrates, no attempt has been made in exploring how substrate stretching affects droplet evaporation and evaporative deposition patterns. Here, we systematically investigate the contact line dynamics of droplets evaporating on substrates with different stiffnesses and stretching ratios and the structures of the evaporative deposition patterns of nanoparticles.
View Article and Find Full Text PDFLife (Basel)
December 2024
Department of Civil Engineering, Zhejiang University of Technology, Hangzhou 310012, China.
The transmission of virus-containing droplets among multiple people in an outdoor environment is seldom evaluated. In this study, an Euler-Lagrange computational fluid dynamics approach was used to investigate the effects of evaporation and the body thermal plume on the dispersion of coughed droplets under various wind conditions, and the infection risk was evaluated for various arrangements of individuals queuing outdoors using virtual manikin models. The evaporation time was longer for larger droplets and in a more humid environment.
View Article and Find Full Text PDFLangmuir
January 2025
CNNFM Lab, School of Mechanical Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563 Tehran, Iran.
This study investigates the impact of cell dynamics on mixing efficiency within a microfluidic droplet, emphasizing the relationship between cell motion, deformability, and resultant asymmetry in velocity and concentration fields. Simulations were conducted for droplets containing encapsulated cells at varying Peclet numbers ( = 100-800) and coupling constants ( = 0.0025, 0.
View Article and Find Full Text PDFSci Rep
January 2025
Pesticide Formulation Research Department, Central Agriculture Pesticides Laboratory, Agricultural Research Center, Alexandria, Egypt.
Soft Matter
January 2025
Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA.
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