Convective Rolls and Hydrothermal Waves in Evaporating Sessile Drops

Langmuir ◽  
2012 ◽  
Vol 28 (31) ◽  
pp. 11433-11439 ◽  
Author(s):  
George Karapetsas ◽  
Omar K. Matar ◽  
Prashant Valluri ◽  
Khellil Sefiane
Keyword(s):  
Convective Rolls ◽  
Sessile Drops

Selection of convective rolls in a thin evaporating-fluid layer in an air flow

2008 ◽  
Vol 43 (1) ◽  
pp. 49-58
Author(s):  
V. P. Reutov ◽  
G. V. Rybushkina
Keyword(s):  
Fluid Layer ◽  
Air Flow ◽  
Convective Rolls ◽  
Selection Of

On the compound sessile drops: configuration boundaries and transitions

2021 ◽  
Vol 917 ◽  
Author(s):  
Chun-Yu Zhang ◽  
Peng Gao ◽  
Er-Qiang Li ◽  
Hang Ding
Keyword(s):  
Sessile Drops

Abstract

scholarly journals Time-Dependent Diffusion Coefficients for Chaotic Advection due to Fluctuations of Convective Rolls

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 99 ◽  
Author(s):  
Kazuma Yamanaka ◽  
Takayuki Narumi ◽  
Megumi Hashiguchi ◽  
Hirotaka Okabe ◽  
Kazuhiro Hara ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Liquid Crystals ◽  
Diffusion Coefficients ◽  
Coarse Graining ◽  
Chaotic Advection ◽  
Time Dependent ◽  
Local Order ◽  
Weak Turbulence ◽  
Normal Diffusion ◽  
Convective Rolls

The properties of chaotic advection arising from defect turbulence, that is, weak turbulence in the electroconvection of nematic liquid crystals, were experimentally investigated. Defect turbulence is a phenomenon in which fluctuations of convective rolls arise and are globally disturbed while maintaining convective rolls locally. The time-dependent diffusion coefficient, as measured from the motion of a tagged particle driven by the turbulence, was used to clarify the dependence of the type of diffusion on coarse-graining time. The results showed that, as coarse-graining time increases, the type of diffusion changes from superdiffusion → subdiffusion → normal diffusion. The change in diffusive properties over the observed timescale reflects the coexistence of local order and global disorder in the defect turbulence.

scholarly journals Evidence of convective rolls in a sunspot penumbra

2008 ◽  
Vol 488 (2) ◽  
pp. L17-L20 ◽  
Author(s):  
V. Zakharov ◽  
J. Hirzberger ◽  
T. L. Riethmüller ◽  
S. K. Solanki ◽  
P. Kobel
Keyword(s):  
Sunspot Penumbra ◽  
Convective Rolls

scholarly journals Sharp transition between coalescence and non-coalescence of sessile drops

2014 ◽  
Vol 743 ◽  
Author(s):  
Stefan Karpitschka ◽  
Hans Riegler
Keyword(s):  
Contact Region ◽  
Threshold Value ◽  
System Control ◽  
Arithmetic Means ◽  
Liquid Body ◽  
Molecular Diffusivity ◽  
Experimental Resolution ◽  
Miscible Liquids ◽  
Phase Angles ◽  
Sessile Drops

AbstractUnexpectedly, under certain conditions, sessile drops from different but completely miscible liquids do not always coalesce instantaneously upon contact: the drop bodies remain separated in a temporary state of non-coalescence, connected through a thin liquid bridge. Here we investigate the transition between the states of instantaneous coalescence and temporary non-coalescence. Experiments reveal that it is barely influenced by viscosities and absolute surface tensions. The main system control parameters for the transition are the arithmetic means of the three-phase angles, $\overline{\Theta }_{a}$, and the surface tension differences $\Delta \gamma $ between the two liquids. These relevant parameters can be combined into a single system parameter, a specific Marangoni number $\widetilde{M}=3\Delta \gamma /(2\overline{\gamma }\overline{\Theta }_{a}^2)$. This $\widetilde{M}$ universally characterizes the coalescence transition behaviour as a function of both the physicochemical liquid properties and the shape of the liquid body in the contact region. The transition occurs at a certain threshold value $\widetilde{M}_t$ and is sharp within the experimental resolution. The experimentally observed threshold value of $\widetilde{M}_t\approx 2$ agrees quantitatively with values obtained by simulations assuming realistic material parameters. The simulations indicate that the absolute value of $\widetilde{M}_t$ very weakly depends on the molecular diffusivity.

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