|
|
| Line 1: |
Line 1: |
| {{About|the physical phenomenon|the band|Capillary Action (band)}}
| | The author's title is Christy. Doing ballet is some thing she would never give up. Office supervising is my profession. Mississippi is the only location I've been residing in but I will have to transfer in a year or two.<br><br>Feel free to visit my web blog: love psychic ([http://grapier.irucomm.com/xe/index.php?mid=member_board&page=1&sort_index=readed_count&order_type=asc&document_srl=488273 http://grapier.irucomm.com/xe/index.php?mid=member_board&page=1&sort_index=readed_count&order_type=asc&document_srl=488273]) |
| [[File:Capillarity.svg|thumb|Capillary action of [[water]] compared to [[Mercury (element)|mercury]], in each case with respect to a polar surface e.g. glass]]
| |
| '''Capillary action''' (sometimes '''capillarity''', '''capillary motion''', or '''wicking''') is the ability of a [[liquid]] to flow in narrow spaces without the assistance of, and in opposition to, external forces like [[Gravitation|gravity]]. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquified carbon fiber, or in a cell. It occurs because of [[intermolecular force]]s between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of [[surface tension]] (which is caused by [[Cohesion (chemistry)|cohesion]] within the liquid) and [[Adhesion|adhesive forces]] between the liquid and container act to lift the liquid. In short, the capillary action is due to the pressure of cohesion and adhesion which cause water to work against gravity.<ref>{{cite web|url=http://science.jrank.org/pages/1182/Capillary-Action.html |title=Capillary Action - Liquid, Water, Force, and Surface - JRank Articles|publisher=Science.jrank.org |date= |accessdate=2013-06-18}}</ref>
| |
| | |
| == History ==
| |
| {{expand section|date=June 2013}}
| |
| [[Albert Einstein]]'s first paper<ref>{{cite web|author=Hans-Josef Kuepper |url=http://www.einstein-website.de/z_physics/wisspub-e.html |title=List of Scientific Publications of Albert Einstein |publisher=Einstein-website.de |date= |accessdate=2013-06-18}}</ref> submitted in 1900 to [[Annalen der Physik]] was on capillarity. It was titled ''Folgerungen aus den Kapillaritätserscheinungen'', which was translated as ''Conclusions from the capillarity phenomena'', found in volume 4, page 513 (published in 1901).
| |
| | |
| == Phenomena and physics of capillary action ==
| |
| | |
| [[File:Capillary Flow Experiment.jpg|thumb|Capillary Flow Experiment to investigate capillary flows and phenomena aboard the [[International Space Station]]]]
| |
| A common apparatus used to demonstrate the first phenomenon is the ''capillary tube''. When the lower end of a vertical glass tube is placed in a liquid, such as water, a concave [[meniscus]] forms. [[Adhesion]] occurs between the fluid and the solid inner wall pulling the liquid column up until there is a sufficient mass of liquid for [[gravitational force]]s to overcome these intermolecular forces. The contact length (around the edge) between the top of the liquid column and the tube is proportional to the diameter of the tube, while the weight of the liquid column is proportional to the square of the tube's diameter. So, a narrow tube will draw a liquid column higher than a wider tube will.
| |
| | |
| == In plants and trees ==
| |
| | |
| The capillary action is enhanced in trees by branching, evaporation at the leaves creating depressurization, and probably by [[osmotic pressure]] added at the roots and possibly at other locations inside the plant, especially when gathering humidity with [[air root]]s.<ref>[http://npand.wordpress.com/2008/08/05/tree-physics-1/ Tree physics] at "Neat, Plausible And" scientific discussion website.</ref><ref>[http://www.wonderquest.com/Redwood.htm Water in Redwood and other trees, mostly by evaporation] article at wonderquest website.</ref>
| |
| | |
| == Examples ==
| |
| Capillary action is essential for the drainage of constantly produced [[tears|tear]] fluid from the eye. Two canaliculi of tiny diameter are present in the inner corner of the [[eyelid]], also called the [[Nasolacrimal duct|lacrimal ducts]]; their openings can be seen with the naked eye within the lacrymal sacs when the eyelids are everted.
| |
| | |
| Wicking is the absorption of a liquid by a material in the manner of a candle wick.
| |
| [[Paper towel]]s absorb liquid through capillary action, allowing a [[Fluid statics|fluid]] to be transferred from a surface to the towel. The small pores of a [[sponge (tool)|sponge]] act as small capillaries, causing it to absorb a comparatively large amount of fluid. Some [[Minecraft|textile fabrics]] are said to use capillary action to "wick" sweat away from the skin. These are often referred to as [[layered clothing#wicking-materials|wicking fabrics]], after the capillary properties of [[candle]] and lamp [[Candle wick|wicks]].
| |
| | |
| Capillary action is observed in [[thin layer chromatography]], in which a solvent moves vertically up a plate via capillary action. In this case the pores are gaps between very small particles.
| |
| | |
| Capillary action draws [[ink]] to the tips of [[fountain pen]] [[nib]]s from a reservoir or cartridge inside the pen.
| |
| | |
| With some pairs of materials, such as [[mercury (element)|mercury]] and glass, the [[intermolecular force]]s within the liquid exceed those between the solid and the liquid, so a [[wikt:convex|convex]] meniscus forms and capillary action works in reverse.
| |
| | |
| In [[hydrology]], capillary action describes the attraction of water molecules to soil particles. Capillary action is responsible for moving [[groundwater]] from wet areas of the soil to dry areas. Differences in soil [[water potential|potential]] (<math>\Psi_m</math>) drive capillary action in soil.
| |
| | |
| == Height of a meniscus == | |
| The height ''h'' of a liquid column is given by:<ref name="Bachelor">[[George Batchelor|G.K. Batchelor]], 'An Introduction To Fluid Dynamics', Cambridge University Press (1967) ISBN 0-521-66396-2</ref>
| |
| :<math>h={{2 \gamma \cos{\theta}}\over{\rho g r}},</math>
| |
| where <math>\scriptstyle \gamma </math> is the liquid-air [[surface tension]] (force/unit length), ''θ'' is the [[contact angle]], ''ρ'' is the [[density]] of liquid (mass/volume), ''g'' is local [[acceleration due to gravity]] (length/square of time<ref>Hsai-Yang Fang, john L. Daniels, Introductory Geotechnical Engineering: An Environmental Perspective</ref>), and ''r'' is [[radius]] of tube (length). Thus the thinner the space in which the water can travel, the further up it goes.
| |
| | |
| For a water-filled glass tube in air at standard laboratory conditions, ''γ'' = 0.0728 N/m at 20 °C,
| |
| ''θ'' = 0° (cos(0) = 1), ''ρ'' is 1000 kg/m<sup>3</sup>, and ''g'' = 9.81 m/s<sup>2</sup>. For these values, the height of the water column is
| |
| :<math>h\approx {{1.48 \times 10^{-5}}\over r} \ \mbox{m}.</math>
| |
| Thus for a {{convert|4|m|ft|abbr=on}} diameter glass tube in lab conditions given above (radius {{convert|2|m|ft|abbr=on}}), the water would rise an unnoticeable {{convert|0.007|mm|in|abbr=on}}. However, for a {{convert|4|cm|in|abbr=on}} diameter tube (radius {{convert|2|cm|in|abbr=on}}), the water would rise {{convert|0.7|mm|in|abbr=on}}, and for a {{convert|0.4|mm|in|abbr=on}} diameter tube (radius {{convert|0.2|mm|in|abbr=on}}), the water would rise {{convert|70|mm|in|abbr=on}}.
| |
| | |
| == Liquid transport in porous media ==
| |
| [[File:Capillary flow brick.jpg|thumb|Capillary flow in a brick, with a sorptivity of 5.0 mm min<sup>-1/2</sup> and a porosity of 0.25.]]
| |
| | |
| When a dry porous medium, such as a [[brick]] or a wick, is brought into contact with a liquid, it will start absorbing the liquid at a rate which decreases over time. For a bar of material with cross-sectional area ''A'' that is wetted on one end, the cumulative volume ''V'' of absorbed liquid after a time ''t'' is
| |
| :<math>V = AS\sqrt{t},</math>
| |
| where ''S'' is the [[sorptivity]] of the medium, with dimensions m/s<sup>1/2</sup> or mm/min<sup>1/2</sup>. The quantity
| |
| :<math>i = \frac{V}{A}</math> | |
| is called the cumulative liquid intake, with the dimension of length. The wetted length of the bar, that is the distance between the wetted end of the bar and the so-called ''wet front'', is dependent on the fraction ''f'' of the volume occupied by liquid. This number ''f'' is the [[porosity]] of the medium; the wetted length is then
| |
| :<math>x = \frac{i}{f} = \frac{S}{f}\sqrt{t}.</math>
| |
| Some authors use the quantity ''S/f'' as the sorptivity.<ref name="hall-hoff">C. Hall, W.D. Hoff, Water transport in brick, stone, and concrete. (2002) [http://books.google.com/books?id=q-QOAAAAQAAJ&lpg=PA131&ots=tq5JxlmMUe&pg=PA131#v=onepage&q&f=false page 131 on Google books]</ref>
| |
| The above description is for the case where gravity and evaporation do not play a role.
| |
| | |
| Sorptivity is a relevant property of building materials, because it affects the amount of [[Damp (structural)#Rising dampness|rising dampness]]. Some values for the sorptivity of building materials are in the table below.
| |
| {| class="wikitable"
| |
| |-
| |
| ! Material || Sorptivity <br> (mm min<sup>-1/2</sup>) || Source
| |
| |-
| |
| | Aerated concrete || 0.54 || <ref name="hall-hoff-p122">Hall and Hoff, p. 122</ref>
| |
| |-
| |
| | Gypsum plaster || 3.50 || <ref name="hall-hoff-p122"/>
| |
| |-
| |
| | Clay brick || 1.16 || <ref name="hall-hoff-p122"/>
| |
| |}
| |
| | |
| == See also ==
| |
| {{Continuum mechanics}}
| |
| *[[Bound water]]
| |
| *[[Capillary fringe]]
| |
| *[[Capillary pressure]]
| |
| *[[Capillary wave]]
| |
| *[[Damp-proof course]]
| |
| *[[Frost flowers]]
| |
| *[[Frost heaving]]
| |
| *[[Hindu milk miracle]]
| |
| *[[Needle ice]]
| |
| *[[Surface tension]]
| |
| *[[Washburn's equation]]
| |
| *[[Water]]
| |
| *[[Wick effect]]
| |
| *[[Young–Laplace equation]]
| |
| | |
| == References ==
| |
| {{Commons category}}
| |
| {{reflist}}
| |
| | |
| {{DEFAULTSORT:Capillary Action}}
| |
| [[Category:Fluid dynamics]]
| |
| [[Category:Hydrology]]
| |