scholarly journals Enhanced interfacial deformation in a Marangoni flow: A measure of the dynamical surface tension

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Rodrigo Leite Pinto ◽  
Sébastien Le Roux ◽  
Isabelle Cantat ◽  
Arnaud Saint-Jalmes
Keyword(s):  
Surface Tension ◽  
Marangoni Flow ◽  
Interfacial Deformation

Interfacial phenomena of molten silicon: Marangoni flow and surface tension

1998 ◽  
Vol 356 (1739) ◽  
pp. 899-909 ◽  
Author(s):  
Taketoshi Hibiya ◽  
Shin Nakamura ◽  
Kusuhiro Mukai ◽  
Zheng–Gang Niu ◽  
Nobuyuki Imaishi ◽  
...  
Keyword(s):  
Surface Tension ◽  
Interfacial Phenomena ◽  
Molten Silicon ◽  
Marangoni Flow

The anomalous wake accompanying bubbles rising in a thin gap: a mechanically forced Marangoni flow

1997 ◽  
Vol 352 ◽  
pp. 283-303 ◽  
Author(s):  
JOHN W. M. BUSH
Keyword(s):  
Surface Tension ◽  
Bubble Surface ◽  
Surface Flow ◽  
Surface Tension Gradient ◽  
Marangoni Flow ◽  
Wake Structure ◽  
Rising Bubble ◽  
Moderate Reynolds Number ◽  
Mechanical Analogue ◽  
Order Of Magnitude

A novel wake structure, observed as penny-shaped air bubbles rise at moderate Reynolds number through a thin layer of water bound between parallel glass plates inclined at a shallow angle relative to the horizontal, is reported. The structure of the wake is revealed through tracking particles suspended in the water. The wake completely encircles the rising bubble, and is characterized by a reverse surface flow or ‘edge jet’ which transports fluid in a thin boundary layer along the bubble surface from the tail to the nose at speeds which are typically an order of magnitude larger than the bubble rise speed. A consistent physical explanation for the wake structure is proposed. The wake is revealed to be a manifestation of the three-dimensionality of the flow in the suspending fluid. The bubble surface advances through a rolling motion, thus generating regions of surface divergence and convergence at, respectively, the leading and trailing edges of the bubble. A nose-to-tail gradient in surfactant concentration is thus established, and the associated surface tension gradient drives the edge jet. The dependence of the wake structure on the suspending fluid is examined experimentally.Surfactants play an anomalous role in the reported flow, serving to promote rather than suppress surface motions. The wake structure is an example of a mechanically forced Marangoni flow, and so represents a mechanical analogue of that accompanying thermocapillary drop motion in microgravity. A theoretical model is developed which reproduces the salient features of the flow, and on the basis of which an estimate is made of the mechanically induced surface tension gradient along the bubble surface.

From viscosity and surface tension to marangoni flow in melts

2003 ◽  
Vol 34 (5) ◽  
pp. 517-523 ◽  
Author(s):  
Shouyi Sun ◽  
Ling Zhang ◽  
Sharif Jahanshahi
Keyword(s):  
Surface Tension ◽  
Marangoni Flow

Dynamics of a fully wetted Marangoni surfer at the fluid–fluid interface

Soft Matter ◽  
2019 ◽  
Vol 15 (10) ◽  
pp. 2284-2291 ◽  
Author(s):  
Harinadha Gidituri ◽  
Mahesh V. Panchagnula ◽  
Andrey Pototsky
Keyword(s):  
Surface Tension ◽  
Fluid Interfaces ◽  
Marangoni Flow ◽  
Fluid Interface

Marangoni flow created by the gradient of surface tension can be used to transport small objects along fluid interfaces.

scholarly journals 3D Nanoparticle Tracking Inside the Silver Nanofluid

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 397
Author(s):  
Saeid Vafaei
Keyword(s):  
Surface Tension ◽  
Silver Nanoparticles ◽  
Triple Line ◽  
Optical Microscope ◽  
Fluorescent Nanoparticles ◽  
Marangoni Flow ◽  
Coated Nanoparticles ◽  
First Time ◽  
Base Liquid ◽  
Ring Phenomenon

Movement of nanoparticle was investigated at the vicinity of silver nanofluid by using a microscope equipped with 100X lens. It was observed that silver nanoparticles were constantly moving inside the nanofluid for the first time. To explore the silver nanoparticle movement, the silver nanofluid was mixed with fluorescent nanoparticles. The coated nanoparticles were tracked three-dimensionally using a Delta Vision Elite inverted optical microscope. It was found that Marangoni flow was a possible reason of the nanoparticle movement which was generated by a gradient of the surface tension at the vicinity of the triple line. A gradient of the surface tension was formed by the segregation of the surfactant from the base liquid at the vicinity of the triple line. The surfactant was separated from the base liquid inside the triple region, since they have different affinities for the substrate. It was also shown that ring phenomenon took place when nanoparticle movement was weak or negligible.

scholarly journals Collision between chemically driven self-propelled drops

2016 ◽  
Vol 806 ◽  
pp. 205-233 ◽  
Author(s):  
Shunsuke Yabunaka ◽  
Natsuhiko Yoshinaga
Keyword(s):  
Surface Tension ◽  
Chemical Reactions ◽  
Bifurcation Point ◽  
Hydrodynamic Interaction ◽  
Concentration Field ◽  
Elastic Collision ◽  
Marangoni Flow ◽  
Reduced Equations ◽  
Isotropic Distribution ◽  
Numerical Approaches

We use analytical and numerical approaches to investigate head-on collisions between two self-propelled drops described as a phase separated binary mixture. Each drop is driven by chemical reactions that isotropically produce or consume the concentration of a third chemical component, which affects the surface tension of the drop. The isotropic distribution of the concentration field is destabilized by motion of the drop, which is created by the Marangoni flow from the concentration-dependent surface tension. This symmetry-breaking self-propulsion is distinct from other self-propulsion mechanisms due to its intrinsic polarity of squirmers and self-phoretic motion; there is a bifurcation point below which the drop is stationary and above which it moves spontaneously. When two drops are moving in the opposite direction along the same axis, their interactions arise from hydrodynamics and concentration overlap. We found that two drops exhibit either an elastic collision or fusion, depending on the distance from their bifurcation point, which may be controlled, for example, by viscosity. An elastic collision occurs when there is a balance between dissipation and the injection of energy by chemical reactions. We derive the reduced equations for the collision between two drops and analyse the contributions from the two interactions. The concentration-mediated interaction is found to dominate the hydrodynamic interaction for a head-on collision.

Surface Tension Driven Film Flow due to Condensation With a Vapor Borne Surfactant

2000 ◽  
Author(s):  
R. Qiao ◽  
Z. Yuan ◽  
K. E. Herold
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Heat And Mass Transfer ◽  
Liquid Surface ◽  
Surface Concentration ◽  
Marangoni Flow ◽  
Absorption Chillers ◽  
Mass Transfer Processes ◽  
Surfactant Transport ◽  
Bottom Side

Abstract In absorption chillers, it is well known that the presence of small amounts of alcohol can enhance the absorber heat and mass transfer significantly. Similar enhancement is also observed in the condenser. Among the theories to explain such phenomena, the recently described Vapor Surfactant theory provides the most comprehensive explanation of the available data. According to this theory, the surfactant arrives at the liquid surface primarily from the vapor. As the water vapor flows toward eventual absorption/condensation, it carries the vapor borne surfactant toward the surface. Once the surfactant arrives at the surface, it tends to concentrate there due to its low solubility and low diffusivity in the liquid as well as the natural affinity of a surfactant for the surface. Non-uniform surface concentration of the surfactant leads to surface tension forces in the liquid surface layer that drive the surface flows often observed. These Marangoni flows are what enhance the heat and mass transfer processes. Although it was often theorized that Marangoni flow plays a role in enhancement, the important role of the vapor has not been well understood. A number of previous attempts have been made to compute Marangoni flow but all such attempts have assumed that the surfactant transport in the liquid is the key. This paper presents calculations of liquid film flows driven by the surfactant as it arrives at the surface from the vapor. This completely new model involves several very interesting features. A two-dimension numerical simulation of such a flow is reported here. The geometry is a thin film (3mm × 10cm) of liquid water with a small patch of cooling centered on the bottom side. The upper surface is exposed to steam+surfactant vapor so that condensation will occur. The model computes the surface concentration of surfactant and relates that to the surface tension. Calculations show that the condensation rate is much higher when Marangoni convection is occurring, even if the surfactant concentration in the vapor is very small (120ppm). This is in accordance with observations in absorption chillers. The result helps to clarify understanding of surfactant-induced enhancement of heat and mass transfer in absorption chillers.

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