Difference between revisions of "Marangoni Effect"

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[[Image: WineTears.jpg|right|300px]]
 
[[Image: WineTears.jpg|right|300px]]
  
The Marangoni effect is the flow of fluid caused by a gradient in surface tension [1,2]. The gradient in surface tension can be caused by a gradient in temperature or chemical concentration [2].  Fluid flows from a region with low surface tension to a region with high surface tension as seen clearly in the following video:
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The Marangoni effect is the flow of fluid caused by a gradient in surface tension [1,2]. The gradient in surface tension can be caused by a gradient in temperature or chemical concentration [1,2].  Fluid flows from a region with low surface tension to a region with high surface tension as seen clearly in the following video:
[http://www.doflick.com/ViewVideo.aspx?t=0&vId=192  Marangoni Effect Example 1]
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[http://www.doflick.com/ViewVideo.aspx?t=0&vId=192  Marangoni Effect Example 1].
  
The tears of wine phenomenon seen in the photo to the right is explained by the Marangoni effect. As alcohol evaporates from a thin layer of wine coating the glass, the surface tension increases. Wine is driven from the bulk up the sides of the glass towards the area of low surface tension until a drop forms, and gravity pulls it back down [2].
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The tears of wine phenomenon seen in the photo to the right is explained by the Marangoni effect. You can observe the phenomenon by swirling some wine in a glass and then setting it down. The thin layer of wine coating the glass above the wine's surface will start developing drops or "tears" which run down the glass. As alcohol evaporates from the thin layer of wine coating the glass, the surface tension increases. Wine is driven from the bulk up the sides of the glass towards the area of high surface tension until a drop forms, and gravity pulls it back down [2].
  
A gradient in chemical concentration causes the surface tension gradient leading to wine tears. [[Influence of Substrate Conductivity on Circulation Reversal in Evaporating Drops|Ristenpart et. al.]] explore a surface tension gradient caused by a thermal gradient across the surface of an evaporating drop.
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In the case of wine tears, a gradient in chemical concentration causes the surface tension gradient. [[Influence of Substrate Conductivity on Circulation Reversal in Evaporating Drops|Ristenpart ''et. al.'']] explore a surface tension gradient caused by a thermal gradient across the surface of an evaporating drop.
  
 
== References ==
 
== References ==
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[1] Velarde, Manuel, "Drops, Liquid Layers and the Marangoni Effect," Philosophical Transactions: Mathematical, Physical and Engineering Sciences '''356''' 829-844 (1998).
 
[1] Velarde, Manuel, "Drops, Liquid Layers and the Marangoni Effect," Philosophical Transactions: Mathematical, Physical and Engineering Sciences '''356''' 829-844 (1998).
  
[2] Mei, C., [http://74.125.93.132/search?q=cache:I90ttwJD8xsJ:web.mit.edu/1.63/www/Lec-notes/Surfacetension/Lecture4.pdf+wine+marangoni&cd=4&hl=en&ct=clnk&gl=us&client=firefox-a "Lecture 4: Marangoni flows,"] [http://web.mit.edu/1.63/www/1.63J/2.21J Fluid Dynamics Lecture Notes] (May 5, 2004).
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[2] Mei, C., [http://74.125.93.132/search?q=cache:I90ttwJD8xsJ:web.mit.edu/1.63/www/Lec-notes/Surfacetension/Lecture4.pdf+wine+marangoni&cd=4&hl=en&ct=clnk&gl=us&client=firefox-a "Lecture 4: Marangoni flows,"] [http://web.mit.edu/1.63/www/ Fluid Dynamics Lecture Notes] (May 5, 2004).

Latest revision as of 12:16, 16 November 2009

Definition

WineTears.jpg

The Marangoni effect is the flow of fluid caused by a gradient in surface tension [1,2]. The gradient in surface tension can be caused by a gradient in temperature or chemical concentration [1,2]. Fluid flows from a region with low surface tension to a region with high surface tension as seen clearly in the following video: Marangoni Effect Example 1.

The tears of wine phenomenon seen in the photo to the right is explained by the Marangoni effect. You can observe the phenomenon by swirling some wine in a glass and then setting it down. The thin layer of wine coating the glass above the wine's surface will start developing drops or "tears" which run down the glass. As alcohol evaporates from the thin layer of wine coating the glass, the surface tension increases. Wine is driven from the bulk up the sides of the glass towards the area of high surface tension until a drop forms, and gravity pulls it back down [2].

In the case of wine tears, a gradient in chemical concentration causes the surface tension gradient. Ristenpart et. al. explore a surface tension gradient caused by a thermal gradient across the surface of an evaporating drop.

References

[1] Velarde, Manuel, "Drops, Liquid Layers and the Marangoni Effect," Philosophical Transactions: Mathematical, Physical and Engineering Sciences 356 829-844 (1998).

[2] Mei, C., "Lecture 4: Marangoni flows," Fluid Dynamics Lecture Notes (May 5, 2004).