# Permeability Definition and 19 Discussions

Permeability in fluid mechanics and the Earth sciences (commonly symbolized as k) is a measure of the ability of a porous material (often, a rock or an unconsolidated material) to allow fluids to pass through it.
The permeability of a medium is related to the porosity, but also to the shapes of the pores in the medium and their level of connectedness. Fluid flows can be influenced in different lithological settings by brittle deformation of rocks in fault zones; the mechanisms by which this occurs are the subject of fault zone hydrogeology.

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1. ### How to Factor Vapor Retarders into Relative Humidity & thus Mold Risk

Relative humidity can be calculated if you know dewpoint and temperature - by formulae such as the August-Roche-Magnus approximation. All methods - all formulae - ignore vapor resistance (perms). Surely scientists/engineers have a way to then, as a subsequent step, bring vapor retarders into...
2. ### Magnetic Field, Field Intensity and Magnetisation

Hello there, I've worked through this problem and I would just like to check whether I've understood it correctly. I found ##\vec H##, ##\vec B## and ##\vec M## using Ampere's Law and the above relations as I would for any thin current carrying wire and these were my answers: \vec H = \frac I...
3. ### Efficiency of heating up aluminum vs steel by induction

Summary: In a heating by induction experiment performed, the idea was to determine the efficiency of heating up a small steel cylinder, an aluminum cylinder and then compare the two efficiencies. The cylinder was surrounded by a metall coil that alternating current was going through...
4. ### Automotive Hydrogen Car Fuel Tank

How do hydrogen powered cars prevent the permeation of hydrogen through the valve used to fill the car's tank with hydrogen? Is a regular check valve used or is the valve special in some way?
5. T

### Magnetic flux and inductance?

If a current flows in a straight wire, a certain amount of magnetic flux will be generated around it. Now suppose I put an iron tube around the wire (but don't change the current). I know the inductance will increase, but is that because more total flux is now being generated, or is the total...
6. ### B Permittivity and Permeability changes

I have a question about permeability and permittivity of free space. Theoretically speaking. If either one or both were to increase in value would that make the speed of light be faster or slower. I know they are constants. I am just curious if they did change what would happen.
7. ### Uncertainty analysis of 2 port measurement

I analyzed uncertainty analysis of 2 port measurement. I referenced 2 book "Transmission Reflection and Short Circuit Line Methods for Measuring Permittivity and Permeability" at pages 31 equation(2.83) "Transmission and Reflection and SCL Permittivity Measurements" at pages 44 equation(2.67)...
8. ### A Diffusion of Hydrogen through Molybdenum alloy

I have been preforming experiments to study the diffusion of Hydrogen through Molybdenum. According to Sievert's law diatomic molecules would diffuse as atoms. But according to my experiments I notice that the flux of hydrogen is directly proportional to the pressure of hydrogen and not to the...
9. ### Need help with permeability of free space.

Homework Statement In a lab that I did in Physics we calculated the magnetic field of a solenoid while constantly increasing the number of time the wire was wrapped around the electromagnet. After I obtained all the values, plotted it in a graph and found the line of best fit, the slope came...
10. ### I Inhibit repulsion between two like poles

Please excuse the lay terms that will follow. I have been doing some reading on "magnetic shielding" and have come across alloys such as MuMetal which have high permeability and so can block interaction between two magnets. My question; Is this inhibition of interaction between the two...
11. ### Electromagnetic wave in glass

Homework Statement A harmonic EM-wave is propagating in glass in the +x-direction. The refractive index of the glass ##n = 1.4##. The wave number of the wave ##k = 30 \ rad/m##. The magnetic portion of the wave is parallel to the y-axis and its amplitude ##H_0 = 0.10A/m##. At ##t=0## and ##x =...
12. ### Magnetic saturartion in 2-D

Dear all, I have a question about magnetic saturation and I can't find any sources addressing my questions. I am relatively familiar with magnetic saturation and that the relative permeability of highly saturated iron becomes rather small. There are numerous sources with figures showing...
13. ### Does classical vacuum permittivity have a QM analog?

According to Maxwell's Equations, the classical vacuum permittivity and permeability have a very important role: They determine the speed of light. But it seems like these two important concepts are not as precisely defined in the quantum world. Are there rigorous analogs of these two...
14. ### Permeability in ferromagnetic material (AC)

Homework Statement The following coil-wound core (core length = L , Gap length = lg, cross- sectional area = A , core permeability = only hysteresis graph is given, N = N turns) is driven by a Voltage source, is known that the current in the coil is 60hz AC. Determine...
15. ### Viscosity, No Slip, Permeable Couette plate

I am trying to understand the no slip condition (parallel velocity =0) in the presence of a permeable surface (in this case a Reverse Osmosis filter mesh ). Does the presence of permeability affect the no slip condition ? Intuitively For a gas Where viscous effects are dominated by momentum...
16. ### Magnetic Moment and permeablity

Hi, I understand that magnetic flux is like electric current and will take the path of least resistance, but I really don't like the current analogy and here's one question where it doesn't help: Say you've got a piece of Ferro Iron where the magnetic moments are not lined up, you put a...
17. ### Looking for what I thought would be a simple Permeability Q

Hi, I've been thinking about how to calculate a permeability curve, I thought this would be an easy to find online but unfortunately I haven't had any luck. From what I can graphically see below: It appears to me that mu for a ferromagnetic material is proportional to the derivative of B vs H...
18. ### Total Magnetic Flux Density Law Problem

We know Total Magnetic Flux B = B_0 + B_m Where, B_0 is the external field and B_m is the field inside a material. Now, we get, B = B_0 + μ_0*M (M is the magnetization) My question is - Do I always have to use μ_0 ? If yes then Why? The material isn't free space, is it? & also B =...
19. ### Problem in Magnetic Field and magnetic effect of electric current

I read in class 10. I am having problem understanding magnetic fields, magnetic flux,magnetic flux density,magnetic field strength,magnetic permeability and strength of magnetic field produced due to a straight and closed loop current carrying conductor at a certain point at a certain distance...