- published: 18 Aug 2014
- views: 74299
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 and construction.
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. It is defined by the ratio:
3 Porosity Hair Tests. How To Find Out Your Hairs Porosity
How to know your porosity & maintain your hair type!
Hair Porosity Test | How -To & SheaMoisture
Hair Porosity 101 ~ (What is Porosity)?
Shea Moisture Low Porosity Line Product Review
HAIR POROSITY 101!
NATURAL HAIR | Know Your Porosity Level
How to Moisturize DRY Low Porosity Natural Hair | Shlinda1
Natural Hair LOW Porosity 101 | Shlinda1
Low Porosity Hair Do's and Dont's
To what do you not drive
Mortal hearts
Accursed hunger for gold?
Cheaply bought, but deadly sold
With new light they shine on through
On fields of shredded goals
Reap crop of clinging hope
Harvest our brave new world
Ancient woe, be gone
Foul illusions of better life
Compared to what, I ask
Does this truth of life coerce?
Juxtaposed they are not