Percolation

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In coffee percolation, soluble compounds leave the coffee grounds and join the water to form coffee. Insoluble compounds (and granulates) remain within the coffee filter.

In physics, chemistry and materials science, percolation (from Latin percōlāre, "to filter" or "trickle through") refers to the movement and filtering of fluids through porous materials.

Background[edit]

During the last decades, percolation theory, an extensive mathematical studies model of percolation, has brought new understanding and techniques to a broad range of topics in physics, materials science, complex networks, epidemiology, and other fields. For example, in geology, percolation refers to filtration of water through soil and permeable rocks. The water flows to recharge the groundwater in the water table and aquifers. In places where infiltration basins or septic drain fields are planned to dispose of substantial amounts of water, a percolation test is needed beforehand to determine whether the intended structure is likely to succeed or fail.

Percolation typically exhibits universality. Statistical physics concepts such as scaling theory, renormalization, phase transition, critical phenomena and fractals are used to characterize percolation properties. Combinatorics is commonly employed to study percolation thresholds.

Due to the complexity involved in obtaining exact results from analytical models of percolation, computer simulations are typically used. The current fastest algorithm for percolation was published in 2000 by Mark Newman and Robert Ziff.[1]

Examples[edit]

  • Coffee percolation, where the solvent is water, the permeable substance is the coffee grounds, and the soluble constituents are the chemical compounds that give coffee its color, taste, and aroma
  • Movement of weathered material down on a slope under the earth's surface
  • Cracking of trees with the presence of two conditions, sunlight and under the influence of pressure
  • Robustness of networks to random and targeted attacks[citation needed]
  • Transport in porous media
  • Epidemic spreading[2][3]
  • Surface roughening[citation needed]
  • Dental Percolation, increase rate of decay under crowns because of a conducive environment for strep mutans and lactobacillus
  • Potential sites for septic systems are tested via the "perk test." Example/theory: A hole (usually 6-10 inches in diameter) is dug in the ground surface (usually 12-24" deep). Water is filled in to the hole and the time is measured for a drop of one inch in the water surface. If the water surface quickly drops, as usually seen in poorly-graded sands, then it is a potentially good place for a septic "leach field." If the hydraulic conductivity of the site is low (usually in clayey and loamy soils) then the site is undesirable.

See also[edit]

References[edit]

  1. ^ Newman, Mark; Ziff, Robert (2000). "Efficient Monte Carlo Algorithm and High-Precision Results for Percolation". Physical Review Letters. American Physical Society. 85 (19): 4104–4107. Bibcode:2000PhRvL..85.4104N. PMID 11056635. arXiv:cond-mat/0005264Freely accessible. doi:10.1103/PhysRevLett.85.4104. Retrieved 19 November 2013. 
  2. ^ Parshani, Roni; Carmi, Shai; Havlin, Shlomo (2010). "Epidemic Threshold for the Susceptible-Infectious-Susceptible Model on Random Networks". Physical Review Letters. 104 (25). Bibcode:2010PhRvL.104y8701P. ISSN 0031-9007. arXiv:0909.3811Freely accessible. doi:10.1103/PhysRevLett.104.258701. 
  3. ^ Grassberger, P. "On the Critical Behavior of the General Epidemic Process and Dynamic Percolation". Mathematical Biosciences. 

Further reading[edit]

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