Imbibition is defined as the displacement of one fluid by another immiscible fluid. This process is controlled and affected by a variety of factors. The capillary number (Ca) and the mobility ratio (M) have the greatest importance. It is also defined as the phenomenon by which the living or dead plant cell absorb water by surface attraction. A classification of imbibition processes was given by Payatakes and Dias:

1. Spontaneous imbibition
2. Constant influx
3. Quasi-static imbibition
4. Dynamic invasion with constant flow rate of the displacing fluid

One example of imbibition that we can find in nature is the absorption of water by hydrophilic colloids. Matrix potential contributes significantly to water in such substances. Examples of plant material which exhibit imbibition are dry seeds before germination. Imbibition can also entrain the genetic clock that controls circadian rhythms in Arabidopsis thaliana and (probably) other plants.

Different types of organic substances have different imbibing capacities. Proteins have a very high imbibing capacity, starch less and cellulose least. That is why proteinaceous pea seeds swell more on imbibition than starchy wheat seeds.

Imbibition of water increases the volume of the imbibant which results in imbibitional pressure. This pressure can be of tremendous magnitude. This fact can be demonstrated by the splitting of rocks by inserting dry wooden stalks in the crevices of rocks and soaking them in water, a technique used by early Egyptians to cleave stone blocks.^[1][2]

[edit] See also

• Dye-transfer process
• Technicolor
• Amott test

[edit] References

1. ^ "Building With Stone". http://www.reshafim.org.il/ad/egypt/building/building_in_stone.htm. 
2. ^ "The Pyramid Puzzle - Deccan Herald". http://www.deccanherald.com/deccanherald/jan62006/sesame144058200615.asp. 

[edit] Further reading

• Muhammad Sahimi, Flow and Transport in Porous Media and Fractured Rock, VCH Verlagsgesellschaft mbH, Weinheim, 1995, ISBN 3-527-29260-8
• M. Alava, M. Dube, and M. Rost, Adv. Phys. 53, 83 (2004).