@Article{icces.2023.09895,
AUTHOR = {Yuhang Wang, Gaojin Li},
TITLE = {Self-swimming of a Droplet Induced by Combined Diffusiophoresis and Marangoni Effects},
JOURNAL = {The International Conference on Computational \& Experimental Engineering and Sciences},
VOLUME = {25},
YEAR = {2023},
NUMBER = {2},
PAGES = {1--2},
URL = {http://www.techscience.com/icces/v25n2/53824},
ISSN = {1933-2815},
ABSTRACT = {The chemically active droplets, which converts the chemical energy into a localized fluid flow at the
interfaces by generating a concentration gradients of surfactant, can realize self-propulsion with complex
trajectories and have been widely studied to mimic the swimming behavior of micro-organisms. In
reality, the motion of chemically active droplets is influenced by a combination of diffusiophoresis and
Marangoni effect under concentration gradients of surfactant. However, the interaction between these
two effects has been only studied for a drop under the constraint of the axial-symmetric motion. To
understand the hydrodynamics of the unconstraint motion, we consider a two-dimensional drop model
to investigate the locomotion of an active droplet characterized by three dimensionless parameters, the
Péclet number (Pe), viscosity ratio (�) and the mobility ratio(m) between the two effects, which can be
either positive or negative depending on the direction of the induced slip velocity influenced by the
interaction state. Through a linear stability analysis, we find that the drop of a negative mobility ratio is
more stable than the ones of positive mobility ratio of the same magnitude under the same Péclet number
and viscosity ratio. Our numerical results show that the droplet state exhibits stationary, steady, periodic,
and chaotic regimes with the growth of Péclet number. The speed of droplet decays as the absolute value
of the mobility ratio increase for the same Péclet number, and this happens more significantly when
mobility ratio is a negative value. The transition from periodic to chaotic regions contains a very narrow
zone for Péclet number where the drop moves in circular and semi-circular motions, and this zone
becomes narrower with increasing mobility ratio. In the periodic regime, the shapes of the trajectories at
a fixed Péclet number and different mobility ratios are closely related to the high-order modes of the
drop, including source dipole and force quadrupole, etc. The strong advection may induce a symmetric
extensile flow and causes the droplet spontaneously to stop between the spontaneous motions. Our
results also indicate that the velocity distribution approximately satisfies the Gaussian distribution law
as Péclet number is large enough in chaotic regime.},
DOI = {10.32604/icces.2023.09895}
}