# What is porosity: Definition and 14 Discussions

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 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam).
There are many ways to test porosity in a substance or part, such as industrial CT scanning.
The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, petrophysics, hydrology, earth sciences, soil mechanics, and engineering.

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1. ### Wyllie time-average equation vs Gardner's equation vs RHG Equation for porosity

If you were estimating porosity from velocity, which approach would you prefer to use among Wyllie time-average equation, Gardner's equation Or RHG Equation, when and why? My answer is RHG equation as wylllie equation don't work for unconsolidate sand and give accurate results when it is...

3. ### Finding a rock porosity change after an acid mix treatment

Homework Statement A 3 wt% HF / 12 wt% HCL treatment is injected without an HCL preflush into a sandstone reservoir containing 10% CaCO3. If half of the HF is consumed in reaction with CaCO3 to form CaF2, what will be the next porosity change, considering both CaCO3 dissolution and CaF2...
4. ### Switchable Porosity: Can Microporous Materials Be Controlled?

Is it possible to switch the porosity of any microporous material by external stimuli (eg. optical, pressure or electrical ). I'm trying to imagine something akin to an "Artificial Stomata" where the pore opening & closing Can be externally controlled. I'd be very thankful if someone could...
5. ### How Many Pores and What Sizes for 20 ppi Porosity in a Metal Foam?

Homework Statement This should be a pretty simple question but I can't find a straight answer in the literature. I want to simulate a 3D model of a metal foam by starting with an aluminum block and filling it with randomly placed spherical holes of constant volume. The foam should have a...
6. ### Simulation of dual porosity in coal using COMSOL Multiphysic

Hi, I would kindly appreciate it if someone could help me with my simulation problem. I am trying to simulate dual porosity in coal and the interaction of coal matrix and fracture flow. The problem I'm having is I can't assign separate domains with different pressures for matrix and fracture in...
7. ### Sphere-Packing porosity development

If you have a large collection of hard sphere's and drop them into a bucket, then shook the bucket, would the sphere's rearrange themselves into a more tightly packed state i.e. lower porosity.
8. ### Porosity Measurement: How to Calculate Factors

how to measure porosity, porosity factor and void factor of a solid mixture?
9. ### Non-destructive testing - Porosity

Hi all, We have a bearing pad at work that failed a porosity test and could not hold pressure (this was the pad itself and not the babbit surface). I need to look into some NDT testing that will give us an idea about the porosity. I have googled and some sites say different things, from...
10. ### Sewer gas and the porosity of concrete

I woke up this morning to find a strong smell of sewer gas in our basement. The smell is gone now. However, I do not know where the exact source is coming from. We had this same issue before with one of the pipes in our basement that runs through the floor and connects to the outgoing...
11. ### Problems that porosity may cause?

I understand the different ways that pores may be formed in a metal, however what i want to know is how it affects the properties of the metal. Am i right in thinking that it would increase the fatigue of the metal, since a large scale of porosity would make the metal more prone to crack formation?
12. ### Error in measuring rock porosity by Archimedes method

The standard way to measure porosity of a rock is to get the pores completely saturated with water, then weigh the rock immersed in water and again in air (there are modified balances for this). Using Archimedes' principle, you then can determine the volume of the rock. Then you dry the rock...
13. ### Is Zeolite the Solution for 1nm Porosity in Water Purification?

Hello all of you! I am new in here. I am working on a project in water purification. I need to know if there is any solid in natural state or artificially made, non toxic, with porosity near 1 nano-meters. I need to use it for final phase of purification, the reversed osmosys process. I know...
14. ### How does porosity effect density measurement?

In one of my classes, we were talking about density measurement and one of the questions that came up was "how does porosity effect density measurement?" I understand that air fills the gaps in the material that is being measured. So is the answer to the question: because air, for example, is...