# Dictionary Definition

porousness n : the property of being porous;
being able to absorb fluids [syn: porosity] [ant: solidity]

# User Contributed Dictionary

## English

# Extensive Definition

Porosity is a measure of the void spaces in a
material, and is measured as a fraction, between 0–1, or as a
percentage between
0–100%. The term porosity is used in multiple fields including
manufacturing, earth sciences and construction.

## Porosity in earth sciences and construction

Used in geology, hydrogeology, soil
science, and building
science, the porosity of a porous
medium (such as rock or
sediment) describes the
fraction of void space in the material, where the void may contain,
for example, air or water. It is defined by the ratio:

- \phi = \frac

where VV is the volume of void-space (such as
fluids) and VT is the total or bulk volume of material, including
the solid and void components. Both the mathematical symbols \phi
and n are used to denote porosity.

Porosity is a fraction between 0 and 1, typically
ranging from less than 0.01 for solid granite to more than 0.5 for
peat and clay, although it may also be
represented in percent terms by multiplying the fraction by
100.

The porosity of a rock, or sedimentary layer, is
an important consideration when attempting to evaluate the
potential volume of water
or hydrocarbons it
may contain. Sedimentary porosities are a complex function of many
factors, including but not limited to: rate of burial, depth of
burial, the nature of the connate fluids, the nature of overlying
sediments (which may impede fluid expulsion). One commonly used
relationship between porosity and depth is given by the Athy (1930)
equation:

- \phi(z) = \phi_0 e^\,

where \phi_0 is the surface porosity, k is the
compaction coefficient (m−1) and z is depth (m).

A value for porosity can alternatively be
calculated from the bulk density
\rho_ and particle
density \rho_:

- \phi = 1-\frac

### Porosity and hydraulic conductivity

Porosity is indirectly related to hydraulic conductivity; for two similar sandy aquifers, the one with a higher porosity will typically have a higher hydraulic conductivity (more open area for the flow of water), but there are many complications to this relationship. Clays, which typically have very low hydraulic conductivity also have very high porosities (due to the structured nature of clay minerals), which means clays can hold a large volume of water per volume of bulk material, but they do not release water very quickly.### Sorting and porosity

## References

porousness in Catalan: Porositat

porousness in German: Porosität

porousness in Spanish: Porosidad

porousness in Persian: تخلخل

porousness in French: Porosité

porousness in Italian: Porosità

porousness in Lithuanian: Poringumas

porousness in Marathi: छिद्रता

porousness in Dutch: Porositeit

porousness in Polish: Porowatość skały

porousness in Portuguese: Porosidade

porousness in Russian: Пористость

porousness in Serbian: Порозност

porousness in Finnish: Huokoisuus

porousness in Ukrainian:
Пористість