Difference between revisions of "Porosity"
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==Definitions== | ==Definitions== | ||
*1a : possessing or full of pores | *1a : possessing or full of pores | ||
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*3: capable of being [[penetrated]] <porous national boundaries> | *3: capable of being [[penetrated]] <porous national boundaries> | ||
==Description== | ==Description== | ||
| − | '''Porosity''' or ''void fraction'' is a measure of the void (i.e., "empty") spaces in a [[material]], and is a fraction of the [[volume]] of voids over the total volume, between 0–1, or as a percentage between 0–100%. The term is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, [[earth science]]s, [ | + | '''Porosity''' or ''void fraction'' is a measure of the void (i.e., "empty") spaces in a [[material]], and is a fraction of the [[volume]] of voids over the total volume, between 0–1, or as a percentage between 0–100%. The term is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, [[earth science]]s, [https://en.wikipedia.org/wiki/Soil_mechanics soil mechanics] and [https://en.wikipedia.org/wiki/Engineering engineering]. |
| − | In gas-liquid [ | + | In gas-liquid [https://en.wikipedia.org/wiki/Two-phase_flow two-phase flow], the void fraction is defined as the fraction of the flow-[[channel]] volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. Void fraction usually varies from location to location in the flow channel (depending on the two-phase [[flow]] pattern). It fluctuates with [[time]] and its [[value]] is usually time averaged. In separated (i.e., non-homogeneous) flow, it is related to volumetric flow rates of the [[gas]] and the [[liquid]] phase, and to the [[ratio]] of the [[velocity]] of the two phases (called ''[https://en.wikipedia.org/wiki/Slip_ratio_(gas-liquid_flow) slip ratio)]''. |
| − | 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]]. [ | + | 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]]. [https://en.wikipedia.org/wiki/Porous] |
[[Category: Earth Science]] | [[Category: Earth Science]] | ||
Latest revision as of 02:32, 13 December 2020
Definitions
- 1a : possessing or full of pores
- b : containing vessels <hardwood is porous>
- 2a : permeable to fluids
- b : permeable to outside influences
- 3: capable of being penetrated <porous national boundaries>
Description
Porosity or void fraction is a measure of the void (i.e., "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%. The term is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, earth sciences, soil mechanics and engineering.
In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. Void fraction usually varies from location to location in the flow channel (depending on the two-phase flow pattern). It fluctuates with time and its value is usually time averaged. In separated (i.e., non-homogeneous) flow, it is related to volumetric flow rates of the gas and the liquid phase, and to the ratio of the velocity of the two phases (called slip ratio).
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. [2]
