Thermal and Concentrational Maragoni Convection at Liquid∕Air Bubble Interface

2005 ◽  
Vol 73 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Konstantin Kostarev ◽  
Antonio Viviani ◽  
Andrew Zuev
Keyword(s):  
Surfactant Concentration ◽  
Thermocapillary Convection ◽  
Marangoni Convection ◽  
Fluid Flows ◽  
Stationary Flow ◽  
Horizontal Cylinder ◽  
Interferometric Method ◽  
Air Bubble ◽  
Stable Temperature ◽  
Stationary Bubble

The paper presents the experimental study of thermo- and solutocapillary Marangoni convection around a gas bubble in an inhomogeneous fluid with a vertical thermal or surfactant concentration gradient. The stationary bubble in the form of a short horizontal cylinder with a free lateral surface was placed into a vertically oriented thin liquid layer (Hele-Shaw cell). The evolution of thermal and concentration fields and fluid flows was studied applying the interferometric method. In contrast to a thermocapillary convection representing a stationary flow and stable temperature distribution, the periodic concentration disturbances around the bubble were observed in the solutocapillary case. The regularities of the discovered effect were revealed, and its interpretation was proposed.

Oscillatory Marangoni convection around the air bubble in a vertical surfactant stratification

2004 ◽  
Vol 332 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Konstantin Kostarev ◽  
Andrew Zuev ◽  
Antonio Viviani
Keyword(s):  
Marangoni Convection ◽  
Air Bubble

scholarly journals Marangoni convection around a ventilated air bubble under microgravity conditions

1994 ◽  
Vol 49 (1) ◽  
pp. 29-39 ◽  
Author(s):  
H.C.J. Hoefsloot ◽  
L.P.B.M. Janssen ◽  
H.W. Hoogstraten
Keyword(s):  
Marangoni Convection ◽  
Air Bubble ◽  
Microgravity Conditions

Bilayer Rayleigh—Marangoni convection: transitions in flow structures at the interface

1995 ◽  
Vol 451 (1942) ◽  
pp. 487-502 ◽  
Keyword(s):  
Crystal Growth ◽  
Marangoni Convection ◽  
Fluid Flows ◽  
Flow Structures ◽  
Fluid Interface ◽  
Lower Phase ◽  
Fluid Physics ◽  
Physically Based ◽  
Flow Mechanisms ◽  
Total Fluid

The fluid physics of buoyancy-driven (Rayleigh) and interfacial tension-driven (Marangoni) convection is examined for two superimposed layers of fluids. This convection occurs on account of temperature gradients that are imposed perpendicular to the fluid-fluid interface. Interfacial deflections, small as they may be, play an important part in identifying the mechanism that governs the flow, and calculations have been made that indicate whether hot or cold fluid flows towards or away from a crest or a trough. As a result, four possible flow structures or ‘modes’ at the interface have been identified. Two heating styles, heating from below and above, are compared and the behaviour of the fluid physics as a function of total fluid depths, depth ratios and gravity levels is explained. Changes in modes result because of changes in these parameters. We have given plausible physically based arguments that predict the sequential change in modes as these parameters are changed and have ‘verified’ our conjectures with calculations. Flow mechanisms in the case of a solidifying lower phase have also been studied, as this has an application to liquid-encapsulated crystal growth. Where convection is deemed detrimental to crystal homogeneity, we conclude that the liquid-encapsulated method of crystal growth is best conducted under Earth’s gravity.

Heat Transfer to Two-Phase: Air, Viscoelastic Fluid Flows Over a Hot Cylinder

2002 ◽  
Author(s):  
B. K. Rao
Keyword(s):  
Heat Transfer ◽  
Liquid Phase ◽  
Viscoelastic Fluid ◽  
Cross Flow ◽  
Fluid Flows ◽  
Horizontal Cylinder ◽  
Two Phase ◽  
Flow Rates ◽  
Heated Cylinder ◽  
Aqueous Polymer

Over a range of 70 < Rea < 9600, 7 < Pra < 130, 0 < ∃ < 0.12 and 0.7 < n < 1, circumferential wall temperatures for air-water and air-aqueous polymer (viscoelastic) solution flows over a horizontal cylinder were measured experimentally. The 2.5-cm-diameter and 7.5-cm-length cylinder was heated by passing direct electric current through it. The peripherally averaged heat transfer coefficient for relatively dilute viscoelastic-air solutions, at any fixed flow rate of liquid phase, increases with ∃. Such increase is more pronounced at lower flow rates of liquid phase. For relatively more elastic solutions, the two-phase heat transfer decreases with increasing ∃. Such reduction is more pronounced at higher flow rates of liquid phase. A new correlation is proposed for predicting the Nusselt number for air-viscoelastic fluid flows over a heated cylinder in cross flow.

Numerical Study of Marangoni: Thermocapillary Convection Influence During Boiling Heat Transfer in Minichannels

2008 ◽  
Author(s):  
Cristina Radulescu ◽  
Anthony J. Robinson
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Thermocapillary Convection ◽  
Numerical Study ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Fully Developed Flow ◽  
Convection Problem ◽  
The Subject ◽  
Stationary Bubble

Marangoni thermocapillary convection and its contribution to heat transfer during boiling has been the subject of some debate in the open literature. Currently, for certain conditions, such as microgravity boiling, is being shown that has a significant contribution to heat transfer [1]. Typically, this phenomenon is investigated for the idealized case of an isolated and stationary bubble resting atop a heated solid which is immersed in a semi-infinite quiescent fluid or within a two-dimensional cavity. However, little information is available with regard to Marangoni heat transfer in miniature confined channels in the presence of a cross flow. As a result, this paper presents a numerical study that investigates the influence of steady thermal Marangoni convection on the fluid dynamics and heat transfer around a bubble during laminar flow of water in a minichannel with the view of developing a refined understanding of boiling heat transfer for such a configuration. This mixed convection problem is investigated for channel Reynolds numbers in the range of 0 ≤Re ≤500 and Marangoni numbers in the range of 0 ≤ Ma ≤ 17114. The influence of the thermocapillary flow is most pronounced for low Re and high Ma numbers showing an average of 40% increase in heat transfer. For low Ma and high Re inertial effects dominate and the thermocapillary effect is not as noticeable. However, the disruption of the fully developed flow does tend to enhance the heat transfer at the expense of additional pressure drop.

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