Questions tagged [porous-media]

Porous media are solid materials that contain interconnected pores allowing fluids to pass through.

Filter by
Sorted by
Tagged with
0 votes
0 answers
18 views

Boussinesq Approximation Term in Momentum Equation

According to the Boussinesq equation: $\rho = \rho_o ( 1 - \beta_t ( t – t_o) - \beta_c ( c – c_o ) ) $ So, $\rho \cdot g$ should be equal to : $\rho g = g \rho_o ( 1 - \beta_t ( t – t_o) - \...
user avatar
  • 1
0 votes
0 answers
16 views

The local and average Nusselt number in a square cavity

I am in the process of programming the local & average Nusselt number in a left vertical wall but my Matlab script gives me inappropriate values and it doesn't change with changing of Rayleigh ...
user avatar
0 votes
0 answers
42 views

Pressure driven vs flux driven

What's the difference between pressure-driven and flux-driven flows in the context of porous media?
user avatar
0 votes
1 answer
21 views

Ability of some porous solids to tentatively sit on water for a while before sinking

How does a porous solid such as the cereal "Wheatena" manage to tentatively sit on water for a while before sinking? I assume it initially somehow evades capillary action, perhaps through ...
user avatar
0 votes
0 answers
26 views

Leaking water from leaky pots

I have two absolutely identical pots with round bottoms. Each bottom has the same number of absolutely identical holes drilled in it. In the first pot, all the holes are quite far apart, while in the ...
user avatar
0 votes
2 answers
59 views

Groundwater flow with external forcing

I want to solve the diffusion equation in porous media with some external forcing at the origin. The regular diffusion equation- $$ \frac{\partial h}{\partial t}=D\nabla^2h $$ But I want to solve for ...
user avatar
1 vote
1 answer
35 views

Which kind of paper has highest absorption speed? [closed]

I am experimenting to analyse the liquid wicking(radial) behaviour of various liquids. I have performed initial studies and experiments on household paper towels but they tend to deform and stick to ...
user avatar
  • 111
2 votes
0 answers
34 views

What does it mean for resistance, as it appears in Ohm's law, to be an integral, evaluated over the body as a whole?

In literature I read: The three linear flux laws mentioned are: As seen, a correspondence exist between the hydraulic conductivity $K$, thermal conductivity $\lambda$, and electrical conductivity $\...
user avatar
  • 1,255
0 votes
1 answer
31 views

Diffusion in porous media - interface flow

i have been working on a problem lately where i think i m missing some basic understanding: I consider the diffusion of a macromolecule in porous media, which i see as Brownian motion through the ...
user avatar
0 votes
0 answers
56 views

Can Friedlander Equations be used to Model Buried Explosive

To quote from WIKIPEDIA The simplest form of a blast wave has been described and termed the Friedlander waveform.[11] It occurs when a high explosive detonates in a free field, that is, with no ...
user avatar
3 votes
1 answer
88 views

Superfluids in areogel and porous media: why?

Aerogels are materials that are like ~90% or more air. As I understand, the topology of the material (i.e. of that part of the aerogel that is not air) is not such that air is contained into bubbles. ...
user avatar
  • 2,935
1 vote
0 answers
34 views

Definition of (fully) saturated porous medium

Let us consider a porous medium and let $\psi$ be a hydraulic head. If $\psi \geq 0$ we say that porous medium is fully saturated, otherwise is unsaturated. How can I imagine saturated porous medium? ...
user avatar
  • 11
0 votes
1 answer
51 views

Porous media flow equation in terms of fluid compressibility and determination of coefficients?

I'm having trouble understanding an equation and solution method given in literature. The 1D flow equation for "high rate" linear gas flow through a porous medium is given as: $$\tag{1} p_1-...
user avatar
  • 1,255
1 vote
1 answer
121 views

Fluid dynamics for the sepiolite

I would like to know some about the physics of an interesting material, the sepiolite. I mean the material from the Wikipedia article Sepiolite where are explained the general and identification ...
user avatar
2 votes
1 answer
142 views

Origin of terms in the Nernst-Planck equation

We know the Nernst Planck equation is $$ \frac{\partial c}{\partial t} = - \nabla \cdot J \quad | \quad J = -\left[ D \nabla c - u c + \frac{Dze}{k_\mathrm{B} T}c\left(\nabla \phi+\frac{\partial \...
user avatar
  • 795
0 votes
0 answers
24 views

What is the relationship between pressure and concentration in liquids in porous media?

I am working on a model in porous media. In particular, it is about the formation damage due to the precipitation. I assigned Dirichlet boundary condition for the concentration near the well-bore, ...
user avatar
1 vote
0 answers
43 views

"Directional" conductivity in linear flux-potential laws?

Question: Has the notion of "directional conductivity" been defined and used in the study of heat flow and electric current flow? Context: The table below gives three laws that describe linear flux-...
user avatar
  • 1,255
1 vote
1 answer
37 views

Reynolds limits on laminar flow between irregular plates (fracture)

I'm trying to understand the limits of laminar flow in a system comprised of two plates of varying width. The idea is to model a naturally fractured system and understand up to when flow and pressure ...
user avatar
  • 113
3 votes
0 answers
69 views

Dimension reducing of heat equation 2D problem

I have two metal objects of different thickness and conductivity: 1) thicker, but poorly conductive. It's properties: $k_1, H$ 2) thin and much better conductive. It's properties: $k_2, h$ ...
user avatar
  • 83
2 votes
1 answer
58 views

What are the assumptions for porous media to be considered as continuum?

The poroelastic models like - Biot theory- are built on the continuum approach. But I am not able to understand, how this heterogeneous media can be considered as a continuum. However, If the porous ...
user avatar
2 votes
2 answers
272 views

What is the meaning of effective density in porous media? Is the density of air inside the pore space not same as density of free air?

I am trying to understand the physical meaning of using effective density in porous media. Is it a fictitious value? Can't I use the density of solid and fluid as it is while modeling porous media?
user avatar
1 vote
0 answers
121 views

Onsager reciprocal relations and Darcy's permeability tensor for anisotropic porous media

The wiki entry on soil tensor permeability states that The tensor is symmetric by the Onsager reciprocal relations Bear & Cheng (2010, p122)* state that: The hydraulic conductivity tensor, $...
user avatar
  • 1,255
2 votes
1 answer
57 views

Acoustics: Construction of the pressure field with transmitted and reflected plane waves

So I have been reading one of the papers about wave manipulation, which takes advantage of the phase shifted reflection by tailoring the design of the system. The design has two domains: air and foam (...
user avatar
  • 151
1 vote
0 answers
25 views

Computing the porosity of a core sample from a set of digital images

Are there any references of books and/or papers about methods to compute the porosity of a given core sample (from an oil and gas reservoir) if this core is given as a set of digital images (for ...
user avatar
0 votes
0 answers
228 views

Can the principal values and directions (axes) of a rock's permeability anisotropy be determined on a single cylindrical core sample?

If a rock core (a right-cylinder of rock), as shown at the left of the image below, has bedding planes oriented arbitrarily with respect to the long axis of the core, how does one go about determining ...
user avatar
  • 1,255
2 votes
2 answers
124 views

Percolation theory: What is the critical amplitude for the "backbone" of a 2-D network?

Disclaimer: I am just learning about percolation theory for the first time, so I am not too familiar with some of the terminology. Suppose you have a 2-D square lattice with bonds connecting sites. ...
user avatar
  • 183
6 votes
1 answer
317 views

Percolation theory: Is there a clear relationship between "probability of connection" and "effective porosity"?

Disclaimer: I am a geophysicist, not a physicist. Sometimes we speak a slightly different language and use different terms. Suppose you have an $N$ x $N$, 2-D rectangular lattice with bonds which ...
user avatar
  • 183
0 votes
1 answer
100 views

Can the coefficient of inertial resistivity ($\beta$-factor) be a 2nd rank tensor?

Question: Can the Forchheimer $\beta$-factor be a 2nd rank tensor (like permeability, $k$)? In most cases in literature, the quadratic Forchheimer equation is applied only to one-dimensional flow. ...
user avatar
  • 1,255
0 votes
1 answer
92 views

Integrating the quadratic Forchheimer equation

Starting with the commonly cited Forchheimer equation: $$\tag{1} -\frac{dp}{ds}=\frac{\mu q}{kA}+\frac{\beta \rho q^2}{A^2}$$ multiplying through by density $$\tag{2} -\rho \frac{dp}{ds}=\frac{\mu \...
user avatar
  • 1,255
1 vote
1 answer
258 views

Darcy's law using Hubbert potential vs pseudo-pressure for a gas

How does one show the equivalence (or difference) of Darcy's law written using Hubbert's potential of a real gas to that of Darcy's law written using the concept of pseudo-pressure (aka pseudo-...
user avatar
  • 1,255
1 vote
0 answers
69 views

When does a finite size random graph percolate?

Assume we are simulating percolation on a 2d lattice. While the system is of finite size, we say that the critical state appears when a cluster connects two opposing ends of the lattice. The bigger ...
user avatar
1 vote
1 answer
575 views

How to implement Hubbert's potential to calculate permeability using Darcy's law?

Question: How does one implement Hubbert's potential to calculate permeability without making assumptions to neglect any aspects of the potential defined by Hubbert? Question's supplemental material: ...
user avatar
  • 1,255
1 vote
0 answers
30 views

Permeability anisotropy of porous media

Imagine if one were to cut a cylindrical plug out of a perfectly homogeneous rock exactly along one of the principal axis of permeability anisotropy, specifically Kmax. Then, imagine inserting only ...
user avatar
  • 1,255
1 vote
1 answer
285 views

Biot coefficient as function of porosity

Can the Biot poroelasticity coefficient $\alpha$ be approximated as a function solely of porosity $\phi$, and if so then how (and under what conditions)? I've read (e.g. 2.02-3 here) that it can, ...
user avatar
  • 755
0 votes
3 answers
187 views

Does groundwater flow depend on the geometry of the aquifer?

I consider two cases of a confined aquifer and want to calculate the pressure / hydraulic head in a quasi 1d case. These two cases are shown in my drawing. I assume homogenious, isotropic darcy flow, ...
user avatar
1 vote
1 answer
2k views

Non-Darcy Flow : Forchheimer plotting method

Recalling Darcy's equation for gas flow, assuming ($z\mu_g$) = Constant $$\tag{1} q_{g,sc}=\frac{kA}{L}\left(\frac{T_{sc}}{Tp_{sc}}\right)\left(\frac{1}{2z\mu_g}\right)(p_1^2-p_2^2)$$ For ...
user avatar
  • 1,255
2 votes
1 answer
903 views

Darcy Flow in porous material - consider porosity in cross-section area?

According to Darcy's Law, the volumetric flow rate Q of a fluid occuring due to a pressure difference $\Delta p$ over a distance L and through a cross-sectional area A of a porous medium (volume V) ...
user avatar
  • 51
4 votes
1 answer
444 views

Can Smoothed-Particle Hydrodynamics (SPH) be used to simulate porous media flow and deformation?

I am trying to use Smoothed-Particle Hydrodynamics (SPH) to study fluid flow in and around porous media. The aim is to observe how it causes erosion and failure. For this, from my understanding, there ...
user avatar
  • 293
6 votes
2 answers
350 views

Are there solid materials with controllable porosity?

In analogy to piezoelectric materials, where the application of an electrical field creates mechanical deformation in the material, I have the following question. Are there solid materials whose ...
user avatar
  • 1,238
4 votes
2 answers
13k views

Can facial surgical mask effectively filter particles of smoke pollution?

Singapore is having an episode of its regular hazy season because of smoke from forest fires. Some people have been using surgical masks like the the one shown at the bottom of this post, presumably ...
user avatar
  • 57
0 votes
1 answer
370 views

Darcy law yields extreme speed for gas flow through packed spheres

The Darcy law is as follows: $$u=-\frac{k}{\mu}\nabla p.$$ Assume we have a gas, then $\mu$ is about $10^{-5}$. For packed spheres a few $\rm mm$ in diameter, $k$ is of order $10^{-8}\ {\rm m^2}$. Say ...
user avatar
  • 195
3 votes
0 answers
172 views

How do I simulate a constant velocity flow in porous media

I am modelling gas combustion in porous media. Most contemporary models assume that the pressure drop from the porous media is small enough to disregard, but I want to include that in my investigation....
user avatar
  • 195
11 votes
1 answer
241 views

How can one build a multi-scale physics model of fluid flow phenomena?

I am working on a problem in Computational Fluid Dynamics, modeling multi-phase fluid flow through porous media. Though there are continuum equations to describe macroscopic flow (darcy's law, ...
user avatar
1 vote
2 answers
6k views

How thin a filter to filter particles out of salt water to make salt for human consumption?

I have gathered some salt in the Death Valley and for the fun of it I would like to clean it and make it edible. The process I plan to follow is simple: Dissolve the salt in water. Boil water for 30 ...
user avatar
  • 13
3 votes
2 answers
559 views

Laws of fluid flow in porous medium

What are the equations that describe the flow of a fluid in a porous medium? Is there a variation of the Navier-Stokes equations? I would like to model the flow of air through a sponge-like structure....
user avatar
  • 381
51 votes
3 answers
15k views

When water climbs up a piece of paper, where is the energy coming from?

Take a glass of water and piece of toilet paper. If you keep the paper vertical, and touch the surface of the water with the tip of the paper, you can see the water being absorbed and climbing up the ...
user avatar
  • 4,771