View source for Capillarity and wetting

[[Main_Page | Home]]
== Introduction ==

"As I glance out my window in the early morning, I can see beads of droplets gracing a spider web...I take my morning shower. The moment I step out, I dry off by way of evaporation and dewetting... As I rush into my car under a pelting rain, my attention is caught by small drops stuck on my windshield... The traffic light suddently turns red. I slam on the breaks and the car skis before finally coming to a halt..Foams are desirable in a shamppoo but can be a nuisance in a dishwasher...A child tosses a stone into a lake. (She) delights in watching capillary waves..."  P.-G. de Gennes; F. Brochard-Wyart; D. Quéré in ''Capillarity and wetting phenomena''; Springer: New York; 2004. (Who else could they possibly be?)
----

== Topics ==
* [[Surface tensions]]
* [[Surface curvature]]
* [[Capillarity]]
* [[Drops, menisci, and lenses]]
* [[Floating and pendant drops]]
* [[Effects of contact angles]]
* [[Flow of thin films]]
* [[Dynamics of forced wetting]]
* [[Dynamics of total wetting]]
* [[Bibliography]]
----

== Extended Reading ==
* de Gennes (2004)
** Chapter 1. Capillarity; Deformable interfaces
*** "A liquid surface can be thought of as a stretched membrane characterized by a surface tension that opposes it's distortion." p. 1
*** Surface tension can be thought of as the energy necessary to increase the area of a liquid, or the force that a surface can exert. p. 4,5 
***"Surface tension is at the origin of the overpressure existing in the interior of drops and bubbles." p. 6
***If there is no pressure difference between either side of a curved surface, then the surface will have zero curvature. p.13
***"High-energy surfaces are those for which the chemical binding energy is of order 1 eV, on which nearly any liquid spreads. High energy surfaces are made of materials that are ionic, covalent, or metallic." p. 18
***"Low-energy surfaces, for which the chemical binding energy is of the order of <i>kT</i>, are generally hardly wettable.  They include molecular crystals and plastics." p. 18 
***"A liquid spreads completely if it is less polarizable than the solid." p. 20
***"Practically no liquid spreads on a fluorinated surface." p. 23 
** Chapter 2. Capillarity and gravity.
***"There exists a particular length, denoted <math> \kappa^{-1} </math>, beyond which gravity becomes important." "The distance<math> \kappa^{-1} </math> is generally of the order a few mm." <math> \kappa^{-1} </math> is the [http://en.wikipedia.org/wiki/Capillary_length capillary length]. p. 33
*** We can also think of <math> \kappa^{-1} </math> as the screening length, meaning that the perturbation due to an object in contact with a horizontal surface will only extend a distance <math> \kappa^{-1} </math>. The decay will be exponential with characteristic length <math> \kappa^{-1} </math>,except very close to the object. p. 34,35
*** "Capillarity will never be able to generate a jet.  In order for a liquid to come gushing out of a tube, it would have to be in a state of overpressure, which would produce an inverted meniscus.  But such a scenario would be incompatible with a rising liquid (which, as we know, implies an underpressure to balance the hydrostatic pressure)." p. 53 
** Chapter 6. Dynamics of the triple line.
*** Concerning the dynamics of total wetting, "It turns out there ahead of the drop is a precursor film a few nanometers thick, which extends much farther out than the drop itself." p. 149
* Krotov; Chapter 7. Some simplest problems of hydrodynamics of capillary systems.
* Starov ; Chapter 1. Surface forces and the equilibrium of liquids on solids.
** "Note that the two ions H<math>^+</math> and OH<math>^-</math> play the most important role in kinetics of wetting and spreading of aqueous solutions." p. 17
----