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# Transport in Porous Media - Science topic

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Hello,
I would like to know how to simulate water diffusion through a porous region using Ansys Fluent. Specifically, I am interested in simulating the following problem:
There is a pipe with insulation covering exposed to atmospheric conditions. Due to the condensation of water vapour at the outer surface of the insulation, water is deposited there. The water then diffuses through the porous insulation layer and reaches the outside of the pipe (inside the insulation). A constant temperature is applied inside the pipe. I would like to know the water content present at the outer surface (inside the insulation) of the pipe.
I am also interested in knowing what kind of inlet boundary needs to be applied.
I understand that this type of simulation is possible with WUFI software, but I believe it is limited to 2D geometry. Therefore, I am interested in how to solve this problem using Ansys Fluent software.
Thank you.
Dear Arun Mathew, the case can be solved by having a 2D axisymmetric boundary so that fluent can solve that in polar coordinates.
After creating the geometry of the inner pipe, the outer porous layer is to be generated as a plane as a FROZEN material so that it will be created as a separate body. Hence it can be defined as a porous media in FLUENT.
In FLUENT,
• Since condensation is a dynamic process, the analysis should be transient
• Enable the energy equation to provide temperature boundaries,
• Import water liquid and water vapour from the fluent library [materials]
• Enable the multiphase model to simulate the mass transfer by condensation [specify the saturation temperature & surface tension in the evaporation and condensation model from the interactions tab].
• Define Water liquid and Water Vapour as two phases in the VOF model
• If there is no forced flow and the flow is driven only by gravity, then you can specify the atmospheric interfaces with the fluid as pressure outlets.
• After initializing, patch the body as water liquid where it is completely water at the 0th timestep.
• Define the required results using the reports tab and run the calculation for the required number of timesteps with the smallest possible timestep size.
I have provided my response to your question. If it has been helpful, please let me know. If you have any further doubts or if my explanation was not clear enough, please do not hesitate to let me know. I am happy to assist you further.
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Hi,
I am trying to model heat and mass transfer in three phases (soil, water & air) porous media. I want to know what equation should I use for the mass transfer rate or mass flux (between water phase and air phase) due to the evaporation of water or condensation of vapors in porous media voids.
There are two class of liquid-vapour mass transfer models available (limited to pore-scale simulation):
#1 First type calculates the mass flux based on KINETIC THEORY, and its derivative models such as Hertz-Knudsen, Schrage-Mills, Lee etc. can be used for large problem domains.
#2 Second type is called ENERGY-JUMP CONDITION, uses thermal resistance at the liquid-vapour interface to calculate the heat flux, which finally calculates the mass flux.
I recommend you to follow this review work:
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In Comsol software, we use the two physics "Heat Transfer in Porous Media" and "Heat Transfer in Solids and Fluids" to study the heat transfer from a porous part to solid and fluid areas. The problem is that the interface between the porous and fluid or solid areas in both physics is defined as thermal insulation. How do we define these common areas boundary conditions to establish the heat transfer between the porous and solid or fluid areas? In some numerical studies, they used the heat flux boundary conditions for the common areas of the porous and fluid sections. Still, I do not think this boundary condition is appropriate.
Bonjour, I think you should activate the extra dimension that is available when you use a porous medium in COMSOL. Coupling of "Heat Transfer in Porous Media" and "Heat Transfer in Solids and Fluids" at boundary conditions.
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I am trying to simulate the heat transfer and fluid flow in a volumetric (porous) solar receiver in COMSOL Multiphysics. I know the material porosity, PPI and thermo-physical properties, however, the exact structural properties, i.e., pore size, solid wall thickness, pore shape, etc., are unknown.
Will it be correct to simulate the computational model as a single domain with given porosity instead of considering the detailed internal structure of the material?
If there is any research article where a similar procedure is adopted, kindly share it with me. I will be thankful to you.
Thanking you
------
Manoj Kumar Sharma
Dear Manoj, I would suggest rereading Section 2.2.1 in the following review paper where it compared the continuum model versus the discrete model:
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I'm currently doing simulations related with contact against porous materials (Tissues) in ABAQUS. As long as I use Pore Pressure=0 as Boundary Condition everything works fine and I'm able to obtain results. The issue is that in the contact area it will be fluid flow out of the material(exudation) due to the compression imposed. The fluid flow is in both contacting zones wich violates the continuity equation.
I've worked with the FLOW subroutine in order to control the boundary conditions in the contact area, and I also have tried the *Contact permeability keyword. I even tried to impose Pore Pressure=0 as an INITIAL boundary conditions.
I have also altered the parameters used to control the solutions (As the maximum number of cutbaks) .
I've read in many places in the ABAQUS MANUAL that by default ABAQUS imposed a sealed boundary condition. I guess this might be true for free contact surfaces but in my case it the program won't run if this BC are not imposed.
Nothing of what I've tried works, the program stops without calculating the very first time increment in all previous cases. Only if I forced the Pore pressure = 0 during the whole simulation, the problem works.
Thanks!
Hi, anyone has solved this problem? Amin Komeili
thanks!
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Any suggestions on analytical and numerical solutions? Any available codes to solve Mathieu equation available other than in math work websites ?
The Mathieu equation has periodic solutions and therefore it is possible to use finite difference approximations to obtain an equivalent matrix eigenvalue problem. The matrix will of tridiagonal kind with an extra two coefficients, one top right and the other bottom left when second order accurate differences are used.
Also see:
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Dear all;
I am trying to simulate non-Newtonian fluid flow in porous media with the help of Palabos software. Palabos is a C+++ open-source library that solves flow problems with the lattice Boltzmann method. I am not familiar with object-oriented programming and I want to extract a value from a template that is used in every iteration. To be more precise; I want to print Omega (which is an (Nx-1)*(Ny-1) dimensional matrix) in every 250 iterations in the form of gif or data to validate my result. I added pcout to print variable in this function and it works but it is repeated every iteration which generates too much data ( imagine 200*200 lattice and 10000 iterations!).
I will be really glad if you could help me through this. the code is provided below. also, I uploaded
.h and .hh file to this message
Many thanks;
Elahe;
template<typename T, template<typename U> class Descriptor,int N>
T CarreauDynamics<T,Descriptor,N>::
getOmegaFromPiAndRhoBar(Array<T,SymmetricTensor<T,Descriptor>::n> const& PiNeq, T rhoBar) const
{
T nu0_nuInfoverCs2 = (global::CarreauParameters().getNu0()-global::CarreauParameters().getNuInf())*Descriptor<T>::invCs2;
T nuInfoverCs2 = global::CarreauParameters().getNuInf()*Descriptor<T>::invCs2;
T nMinusOneOverTwo = (global::CarreauParameters().getExponent() - (T)1)/(T)2;
T lambdaOverCs2sqr = global::CarreauParameters().getLambda()*Descriptor<T>::invCs2;
lambdaOverCs2sqr *= lambdaOverCs2sqr;
T piNeqNormSqr = SymmetricTensor<T,Descriptor>::tensorNormSqr(PiNeq);
T alpha = lambdaOverCs2sqr * piNeqNormSqr *(T)0.5
*Descriptor<T>::invRho(rhoBar)*Descriptor<T>::invRho(rhoBar);
T omega = carreauDynamicsTemplates<T,N>::fromPiAndRhoToOmega(alpha, nu0_nuInfoverCs2, nuInfoverCs2, nMinusOneOverTwo, this->getOmega());
T tau=(T)1/ omega;
T visco=((T)2 * tau - (T)1)/(T)6;
pcout << "" << visco << std::endl;
return omega;
}
Dear all;
I searched among some examples and I figured out that an output image for omega could be easily generated by adding these few lines to the writeGifs function in the CPP file.
imageWriter.writeScaledGif(createFileName("omega", iter, 6),*computeOmega(lattice , Box2D(0,nx-1, 0,ny-1)),
imSize, imSize );
Regards;
Elahe
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I am looking into the permeation of gases through porous metallic sintered plates when different pressures are applied on either sides of the plate. Darcy's permeabilities and Forchheimer's constants of the plates are known. My aim is to predict the flow through such plates depending on the pressure differences.
I have found a model where the Darcy-Forchheimer-Equation is integrated into the Navier-Stokes-equations, and simple block meshing and finite volumes are very suitable for the prediction of throughput through the plates (at least in my opinion). However, the Darcy-Forchheimer-equation in Navier-Stokes is a velocity dependent source term and the experiments are quite similar to shock-tubes (High-Pressure on one side, low pressure on the other and inside the sintered plate as initial condition).
I wrote a simple simulation in Python which did not work. I think the reason for this is that energy conservation is broken because of the velocity dependence of the source term and the shock-type initial condition. Do you have any idea where I can find references / computer codes (Fortran, Matlab, Python) which would help me with my problem?
I think that you should revisit the derivation of the Navier-Stokes equations and take a look at the work by KR. Rajagopal et al.
Rajagopal, KR. On implicit constitutive theories for fluids. J Fluid Mech 2006; 550: 243–249.
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I'm using ANSYS Fluent 2019 with Space claim, my problem is involving moisture diffusion (therefore using Species transport). I found that my h2o can never pass through the porous zone.
I have tried varous porosity value, viscous resistance, with and without UDF of different diffusivity, and even (in space claim): shared topology or without shared topology but with contact. Do anyone know how to fix this?
Take a look at this paper:
DOI: 10.1615/JPorMedia.2021025407
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Hello friends,
I intend to simulate the cementation process in porous media (i.e. granular soil). I'm not sure if I can model the cement slurry as a mere fluid with high viscosity and density. If it is possible, does it act as a Newtonian fluid or as a non-Newtonian one? If the slurry cannot be accurately modeled as a fluid, how can one simulate the flow of cement slurry/paste in a porous medium?
Any suggestion is appreciated. Thanks a lot in advance.
For a cement slurry for oil and gas wells its rheological characterisation has been carried out by many authors (i.e. Bourgoyne A. et al 1991, Technip 1982 and many of the service company manuals/books & publications). This characterisation has been based on a number of assumptions such as that temperature has no influence on the rheology until the slurry is in place. In other words that its rheological behaviour is either assumed at surface or downhole temperature and prior to the onset of dehydration and setting of the slurry. Passage of the slurry through the porous media (invasion) has been modelled by Chin W. (Formation Invasion 1995) which is worth reading. Invasion (Also know as filtrate invasion) can also be modelled using the algorithms used to calculate fluid loss in fracturing treatments, they are based on viscosity, pressure and rock properties. These can be found in most manuals of hydraulic fracturing. I hope it helps
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Fluid flow in porous media depends on shear rate and shear stress. The effective viscosity of the fluid can be determined using Darcy's law. We know that shear rate and shear stress varies along radial direction during the flow of fluid in a pipe. Do we have any similar method to determine the variation of shear rate and shear stress in porous media?
A small matter in the scheme of things..... in the question you have mixed singular and plural. It should end with either, "in a porous medium" or "in porous media". This grammatical error is very widespread indeed and about 1/3rd of papers that I review have the error. Perhaps this is because one hears "the news media" being treated as a single group.
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Dear All,
Any one knows how to model a 1D Advection Diffusion example on abaqus.
Regards,
have you an example of 1D Advection Diffusion
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Dear all,
I want to compare differences in the drainage capillary pressure curves for different simulations with experimental data. I want to show how close or far I am from the experimental data. What would be the most elegant solution? The orange line is the capillary pressure from experimental data.
Best,
Alex
I don't really understand how rank correlation could be helpful here. If both curves (experimental and simulated) are strinktly monotonousley increasing, the rank correlation will be perfect, no matter how similar the two curves are.
I think the Kolmogorov-Sminov statistic should be a natural choice (https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test).
If you can take the saturation (as a variable strincly in (0,1)) as a probability value, you might even use the Kulback-Leibler divergence to measure the (dis-)similarity between two curves (https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence).
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I want to find the analytical solution of a radial diffusion system (1D cylindrical coordinates). Here what is considered is pressure diffusion. The conditions are simple and similar to the following.
Initial P = P0
P(r=infinite) = P0
P (r= 0) = P1 when t > 0
I need the solution of P at any r_i and t.
The flow rate term is unknown.
Could anyone give any suggestion? Thank you.
see
Radial symmetry of solutions to diffusion equations with discontinuous nonlinearities
Joaquim SerraJournal:Journal of Differential EquationsYear:2013
best luck
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• Dear all,
• I am trying to understand the data I collected when flowing water through a matrix of agarose gel (2% w/v) encapsulated in a tube giving a matrix dimensions of 2 mm in diameter and 20 mm in length. This agarose matrix is attached through the tube to a syringe pump working at flowrates in the range of ul/hr
• From my understanding, given this flowrate, this flow regime is truly dominated by viscous forces and should be described by Darcy's Law and Kozeny-Carman Equation. However, as you can see in the graphs, once pressure reaches a stable point, it starts oscillating.
• My question then is, does anybody understand why these oscillations happen and how can be explain them? I assume since Darcy's law draws a linear relation between Pressure Gradient and velocity using the permeability parameter, that these permeability is the one changing and affecting P. However, I have not yet found an answer in literature
Dear Albero,
This is not my area of expertise at all, but we have previously looked at the viosco-elastic properties of biofilms, and have recently looked at the impact of increasing liquid viscosity on biofilm-formation.
I would presume the oscillations you see are the effects of random vibrations of small sections of the agarose network stretching and recovering in the water flow. This should be random, but as parts of the agarose bock start to vibrate in synchrony, the amplitude of the vibrations should increase until sections of the agar break and you get less restricted liquid flow through that part. Perhaps you could test this, as I would assume that below some critical flow rate (perhaps related to the agarose/gel concentration) the vibrations would not start to buildup, and above this the rate of failure should increase as fluid flow increases. You could also look to see what happens if you stiffen up the agarose gel (using different suppliers, using metal ions, etc.) or increase the viscosity of the fluid you use!
Hope this helps, Andrew.
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hello everyone,
I need your help. I was meshing a porous media geometry with ICEM, and after meshing, I wanted to transfer the data to #fluent, I encountered this error "WARNING: Mesh has uncovered edges. ANSYS Fluent needs a complete boundary (lines in 2D) or it will give a variety of errors and not read in the mesh! If this was 2D Hexa, perhaps your edges are not associated with perimeter curves".
P.S. in the attachment I'll upload an image of the geometry.
Adib Amini be welcome, I hope you fix the problems!
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Filtration
Il est préférable d'utiliser un mélange poreux de différents matériaux bien choisi.
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I have been trying to model the electrical double layer for geopolymer. But, I could not get any equations or simulation pathways that would help me calculate charge available at the surface of the materials.
Can you help me on this?
An electrical double layer is being studied to modify cement for various applications. Cement is a complex mixture of oxides that hydrate differently depending on the composition of the cement and their concentration in the solution. It is impossible to mathematically simulate a double layer. You can take one oxide and work with it to simulate a double layer experiment.
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I conducted experiments of adsorption/desorption of a mixture of compounds on macro porous resin in fixed-bed continuous-flow and I calculated the experimental and the theoretical stoichiometric times. What is the meaning of the stoichiometric time? it refers to what exactly?
By Alan Gabelman, P.E.
American Institute of Chemical Engineers (AIChE) (2017)
Good work and my best regards, Pierluigi Traverso.
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I am finding some conflicting literature on flow properties of metal foam/porous media. While some text books consider it as property of the porous media, some literature suggest that it vary with fluid.
1. Work of Dyga et al. - experimental determination of flow properties with air, water and oil - about 30% deviation in permeability (open access link : )
2. Word of Bodla et al. - microtomography based study - with air and water, up to 17% deviation in form drag coefficient, up to 2% variation in permeability (link :
• )
3. Work of Wilson et al. - //Permeability and form coefficient are two main hydraulic properties that characterize any porous medium. Once determined, they are global parameters, i.e., valid for the entire porous medium. Under isothermal conditions, they are independent of the properties and flow conditions of the fluid flowing through the porous medium.// (link: )
What is the correct approach?
The Influence of fluid property on permeability and form drag coefficient is characterized by the friction factors fv, fD, fi and ft. The total friction factor ft depends mainly on both Reynolds number Re, and Darcy number (Dp and φ). Three regions for the behavior appear
 Re≤100, fi is negligible, fD and fv shares with the main part.
 100≤ Re≤10000 , transition region in which the two types of friction factors fD and fv decrease sharply while the inertia friction factor fi increases sharply.
 Re>10000 , ft curve overlaps with the line of fi, the two types of friction fD and fv are neglected and fi/ft asymptotes to the value 1. i.e. the flow depends mainly on the inertia friction fi which is constant with Re.
You can find additional details in the attached file
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Hello!
I would like to understand in what cases blood or some other biological liquid passes through implant or graft with some porous microstructure according the Darcy law (thanks to the pressure differences).
I have an idea to produce a research about blood permeability through various implants microstructure, but unfortunately it is harder than I thought to found some justification in literature that blood actually could pass through such microstructure due the Darcy law. Thus, I would be grateful for your help in this question - maybe you have some papers about it or some other helpful stuff.
Sincerely, Catherine
Gamal Bedair , at this stage I think yes, thank you. I will discuss with my colleague who has an experimental machine about further details and maybe new questions will appear.
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For a 3D single phase turbulent Air flow inside a partially filled channel with porous material, what kind of interface treatment does ANSYS Fluent use for the interface between a porous and a fluid zone by default?
I know there are different interface conditions such as The Ene, Levy and Sanchez-Palencia interface, The Beavers-Joseph interface, but i want to know which interface conditions does ANSYS Fluent use.
For the porous zone Forchheimer extended Darcy’s equation and the thermal equilibrium model have been employed and the flow has been considered as laminar flow, but for the fluid cell zone the flow is turbulent and RNG k-Epsilon turbulence modeling has been utilized.
Yeah, of course.
No one answered this question here, so i asked this question on CFD-Online's forum. A user named LuckyTran gave me this answer:
"I don't think there is any special interface treatment.
When you select the laminar zone option, Fluent sets the turbulent production in that zone to zero. The variables (k, epsilon, etc.) are still transported through the laminar zone.
There is another option (accessed using TUI commands) that allows you to also set the turbulent viscosity to zero in the laminar zone. But again, they are simply transported.
The pressure drop due to the porous media is handled by adding an extra volumetric momentum sink. If you need a reference, refer to the user manual section on Porous Media Conditions (see 7.2.1-3).
There is only one momentum equation. Refer to my previous post for why there is only one momentum equation when you use a laminar zone option. Interface treatment is needed in general when you actually have two separate sets of governing equations. But that is not the case."
(the link for this discussion on CFD-Online's forum:
I wrote my understanding from this statements for the reviewer, fortunately, he/she accepted it and here is our published paper:
Best regards.
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Could anyone tell me how large usually the magitude of induced pore pressure changes during a well-drilling in an aquifer? In my case, it is a near 200 m deep well. Perhaps the induced pore pressure is related to the drilling mud? If possible, please give a reference. Thank you.
Thank you. After some internet survey, I find that during drilling there is a pump to control the pressure of drilling mud , which is used for carry cuttings out of the hole. However, I do not know the setting pressure of the pump.
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I have an unknown sample to characterize using different techniques (mainly pore size distribution):
-X-ray computed tomography
-Mercury intrusion porosimetry
-Gas porosimetry
-BET tests for the surface area.
how would you proceed to make a perfect analysis (taking into consideration the time/money/precision factor)?
Any explanation, recommendation and/or articles for comparative studies would be a perfect help. Thank you in advance.
Moustafa
For unknown materials, a BET surface area analysis (by gas adsorption) is a good place to start... this at least will reveal how much gas accessible surface there is and one can make certain inferences about the extent of meso and microporosity by combing the BET calculation with the t-plot method. A complete description of (gas accessible) micropore space requires low relative pressure gas adsorption isotherms and appropriate mathematical models (DFT, not BJH for micropores). Remember that gas molecular/atomic size plays a role in accessing the smallest of micropores; CO2 at 273K can access smaller pores than can N2 at 77K for example. Mesopore and small macropore size distribution can be done by gas adsorption up to a few hundred nm pore diameter. Gas adsorption isotherm hysteresis can reveal something about the connectivity of pores. Larger macropores are quickly evaluated using mercury intrusion porosimetry... up to ~1mm in diameter. The value of these fluid-based methods (gas adsorption and mercury intrusion) is that pore volume can be known directly, unlike diffraction and microscopy techniques. They still have a role to play of course to understand the underlying solid structure that is giving rise to the porosity. CAT scans can be useful in the meso/macro scale but cannot easily give quantitative values and of course rely on good X-ray contrast. Small angle scattering techniques really come into their own for amorphous and soft materials.
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Could anyone tell me that where can I find an analytical solution of diffusion equation (PDE) with 1D zero flux boundary at outlet? I need this for calculating rock permeability from pressure diffusion.
I have found there are some literatures giving solution in a semi-inifinite domain. What I want to get is an analytical solution in a finite domain with at x=0, c =C0 and at x =L, flux = 0.
Thank you.
1- As said above by Pascale: Conduction of heat in solids by Carslaw and Jaeger.
2- The mathematics of diffusion by John Crank.
3- Cannon JR (2008) The one-dimensional heat equation, encyclopedia of mathematics and its applications. Cambridge University Press, Cambridge.
4- van Genuchten MT, Alves WJ (1982), Analytical solutions of the one-dimensional convective–dispersive solute transport equation. U.S. Department of Agriculture, Technical, Bulletin No. 1661, p 151.
5- A. D. Polyanin and V. F. Zaitsev, Handbook of Exact Solutions for Ordinary/Partial/Nonlinear Differential Equations, 2nd Edition, Chapman & Hall/CRC Press, Boca Raton, 2003
(Last one is a series on books)
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I need to simulate the transition of Flow through Coarse Porous Media such as Rock-fill dams, to investigation of Water level profile in each distance from up-stream and determination of discharge of fluid seepage from the body of these media. Notice, I want to simulate a Single-Phase Flow.
How can I simulate this project? Please suggest and introduce a useful software for this issue to me...
Dear Dr. Majid Heydari ,
It would be appreciated if you explain more about the method you used to simulate the POROUS MEDIA for your Ph.D. thesis.
Best regards,
Mehdi
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Hi,
I need to set a porous zone (as radiator) in fluent. But I dont know any about the inputs like viscous resistance or velocity resistance coefficients. For a panel radiator for example, how can I determine these factors. cooling air will go through the small sections(ducts) between the radiator panels.
Separate the domain(s) that you want it to be as a porous media in your problem by selecting "add frozen" option in "Geometry" section. Then choose a certain name for your porous media domain in order to be distinguished from other domains. Next, go to "setup" section and select "cell zone conditions". Then, double click on porous media zone determined in previous step. Now, you can check "porous zone" and insert your porous media details such as porosity and permeability.
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Lets say I want a disc shaped porous medium with 3mm thickness and 15mm radius but with holes of a certain shape and size (lets say squares with 3mm2 area)
Possible?
Currently I'm actually modeling the porous region but I think using Porous media would be a better choice overall
I understand your situation. I faced that situation in my PhD 2nd publication.
You want to use porous media model because the computational cost using the real geometry of hole shape is too high.
In porous media, you can mimic the hole shape behavior by modifying the permeability (inverse resistance) and dynamic loss through an User Defined Function (UDF) macro in Fluent named as DEFINE_PROFILE. Here is an example of that macro:
#include "udf.h" DEFINE_PROFILE(porosity_function, t, nv) { cell_t c; real time=CURRENT_TIME; begin_c_loop(c,t) { C_PROFILE(c,t,nv) = 5000000000000+2000000000000*time+4000000000*pow(time,2); } end_c_loop(c,t) }
Now the problem is determination of important parameters that can represent the hole shape behavior. You can follow our multi-scale CFD approach in those papers:
The general idea of this method is: We do the CFD for dual scales where the bigger scale is porous media, the smaller scale is real hole shape but just for a representative element volume (you can use 1 hole or several holes). In the smaller scale, you need to run the simulation for a wide range of BC to capture the full range possible in the bigger scale.
I hope you enjoy it.
Good luck.
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Hello All,
I'm new to porous media simulations. I'm trying to create a pressure drop using porous media. I plotted the velocity vs dP/L and curved fitted using the equation Ax^2+Bx. I used A as inertial resistance and B as viscous resistance. My viscous resistance value is one order of magnitude less than the inertial resistance. Kindly let me know if this trend is acceptable, I heard from some that the viscous resistance should always be higher than the inertial resistance. I can provide more info if needed. Thank you.
Dear Bharath Ram Ravi,
The ratio of inertial to viscous resistance in a porous media depends for a STEADY flow (constant pressure difference imposed across the medium) on the Reynolds number Re defined as: Re=U d/nu. U is a characteristic flow velocity (filter velocity), d is a typical pore diameter and nu is the kinematic viscosity (dynamic viscosity divided by density) of the fluid. For an imposed harmonic unsteady pressure difference with frequency f one should consider the ratio of unsteady inertial force and viscous forces ( 2 pi f U)/(nu U/d^2)=(2 pi f d^2)/nu, where pi=3.14... Hence the answer depends on the characteristic flow conditions you are considering. These are best described in terms of dimensionless numbers. Regards, Mico
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I am doing a column experiment in saturated porous media, using different P concentration effects on the transport of ferrihydrite colloids. I got a 5 ml effluent for every sample. I divided that in two parts. The 2.5 ml I used for measuring soluble P after centrifuge and filtration with 0.22 um filter membrane and measured via Murphy and riley method. while for TOTAL PHOSPHORUS, I took 1 ml of effluent and digested with 4 ml of 6M HCL for 24 hrs as per the digestion process for ferrihydrite colloids described in literature and then I used p-nitrophenol indicator (yellow indicator) and neutralized sample with 4M NaOH and 0.1 HCl. and then after neutralizing the sample I measured total P with murphy and riley (1962) method. My question is that, Is that the right way of measuring total P? I got good results by the way but need opinion from experts...
Veli Uygur Yes Sir, I prepared ferrihydrite with different concentrations of P, and confirmed. but I didn't find a suitable reference for my work i.e. the digestion of P sorbed iron colloids, the way I did.
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Dear community,
I am interested in modeling capillary forces in porous media using the VOF model. The reason for using VOF is mere because of stability. Eulerian-Eulerian is too sensible to IC and most of the case it just diverges or blows up.
I have reviewed the literature and I found two interesting papers, that shed some light on how to determine the capillarity pressure and force in a porous media based on the porosity and permeability. Interested readers refer to:
2.-
These two works made great work defining such parameters. However, when we are modeling extra terms in VOF, we need to include those as a volumetric source term (body force) at least in STARCCM+.
My question is how to cast that force that represents the net force on the pad when a "radius of equivalent capillary " is used to represent the porous media.
So far, I've failed at casting that term into a body force source term. One thing that needs to be check is that the sum of the gravity force (another body force) + the net capillary force must be positive. In my case, I still have a negative number, meaning that my capillarity force is not big enough to overcome gravity.
Any suggestion ??
Julio
I agree
Leander Boer
der Boer but, I’m using a porous region in CCM+z I forgot to mention that. As result my porous region does not explicitly solve the porous medium. instead it uses Viscous and inertial coefficient resistance to determine the pressure drop. That’s why I wanted to include a force mimicking the capillary force counteracting the gravity.
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I'm looking for codes that can do this for saturated and/or unsaturated porous media. I expect there are a few that can handle the porosity changes easily, but predicting permeability changes seems much more complicated.
Dear Spencer,
In this benchmark exercise you have 5 codes that can do so:
In this other benchmark you have a couple of codes more:
I hope this helps you
Best regards
Vanessa
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just to update the community and people interested in the problem.
I read that if and only if when one apply porous jump as the boundary condition, FLUENT would only consider flows perpendicular to the actual surface. That is definitely not our case. In particular, our system doesn’t possess inlet and/or outlet flows (or it doesn’t have to be perpendicular specifically), since it will be a real earth model simulation which will be representing fluid dynamics and it’s chemical interactions through 3-layered marine sediment. So, we are interested in natural flow of the water liquid in the undermost body, chemical interactions and outcomes of it in the middle body, once again natural flow of the water liquid and products from the reaction in the uppermost body by time, i.e. we solve the system as transient. As you can see, it’s not like a flow through cylindrical objects etc., thus it’s totally different. Today, we conclude that we need to figure out another option for boundary condition, since porous jump seems a bit non-functional.Once again the main fault we encounter when we run the program is most likely arised from enforcing a chemical reaction just in the middle body. Now, I am searching for some answers regarding how to enforce a chemical reaction just in a specific region(in our case in the middle) of a body.
My system is composed of 3 bodies, and the middle body will be the host of a reaction. All those three systems have the porous zone option activated. I want the water liquid which flows through the undermost body and arriving the porous jump boundary, passing through this boundary, reacting with the chemicals I designated in the middle body, creating those other products, and finally once again those products for this time passing through the second porous jump boundary and reaching to the uppermost body.
I hope you could imagine the system. Now I created 2 cell zones just above these porous jump boundaries with a width of 1 grid cell which was 8 m for my case, and also set the Y velocities of those interior cell zones as 0. Logically, since they are just above the porous jump boundaries they are actually in-situ of the reaction area(the middle body). So, I did activate the porous zone and reaction options for my cell zones, and set '0' value for the Y velocities in the fixed values tab (A researcher who encountered the same problem proposed this method, so I wanted to give it a try.).
Now, as for porous jump boundaries, I still set them as porous jump boundaries which I believe where the problem arises. When I didn't create a namedselections for them in mesh section, ANSYS Fluent gives the error for example:
Error: Species are not solved in neighbor cell threads (14 and 16)\n of interior zone 6. \n
Error Object: #f
but when I set them as porous jump boundaries, this time it gives an error of segmentation fault, no flow detected at porous jump 7(exp.).
One more thing, the properties of the porous jump condition:
FACE PERMEABILITY: 1e+10(default) How do I set it, I have a mesh system of 5000x5000 m and 40000 elements(grids) in this system
POROUS MEDIUM THICKNESS: 0 it is.
PRESSURE-JUMP COEFFICIENT: 0(default) I saw some calculations for cylindirical studies but I don't know how to calculate it or what are the values for 2D planar structures(systems).
What is it that I'm doing completely wrong and/or fail to notice?
Any comment would be much appreciated. Thanks in advance.
Cheers,
Selvi
Try to run without porous zone first to sure the mesh interface was corrected.
Usually the BC between two porous layers is interior. The things that make them be different are permeability and porosity.
In Fluent, there is no permeability (K), but the viscous resistance (1/K) in the form of momentum source term.
In case that your permeability is extreme high, you can increase it gradually. But the value of K in your case is not so high, so you can apply it directly.
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Hello all,
I am looking for applications or systems where two phases, wherein one is Newtonian while other is non-Newtonian of both are non-Newtonian are involved.
Some initial search do gives some broad fields like bio-medical, chemical process but I am looking for more precise examples.
It would be kind to seek some answers.
Thanks
You can use star ccm+, in this software you can define most fluids such an
Newtonian and non-Newtonian and chemical process and multiphase of them.
Best Regards
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I am modelling a flow through porous media using ANSYS Fluent. The flow through porous media is assumed to be laminar. Shall I need to check y+ value in the porous zone also?
Dear Mr.Parag C,
Y+ is only needed for turbulent flows. However as yours is a laminar flow problem you need not worry about it.
Thanks.
Saurav
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Hey everyone,
I'm trying to simulate a porous media column that's initially saturated with water, and get's progresively filled with air from the top. For water to move, the driving force is gravity, but in COMSOL there's no possibility of applying either gravity or volume forces to a domain when using this physics package.
Is there a stablished way to implement gravity in this kind of model, either through weak contributions or any other method?
Sounds great! All the best.
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Hello, I am trying to solve these PDE's (see the attached file) but I could not find the appropriate method to solve these equations. Can anyone suggest me which method of PDE is suitable to solve these equations?
Please guide me it will be highly appreciated.
Thank you.
If you have no experience of numerical methods, then I would suggest that you should start with something straightforward in order to build up your expertise and experience. Just having someone else's code will give you no long-term skills. Perhaps a good starting point might be to solve Fourier's equation, theta_t = theta_xx, subject to the initial condition, theta=sin(pi*x) at t=0 and the boundary conditions, theta=0 at x=0,1. Forward differences should be used in time, and central differences in space. The analytical solution is theta=exp(-t)*sin(pi*x) for comparison purposes. Details on how to discretise this may be found in any textbook which covers the numerical solution of PDEs. In addition, when you have a working code, then you will notice that the method becomes numerically unstable when dt > 0.5 dx^2, and therefore timesteps need to be smaller than (dx^2)/2 so that the numerical solution decays just as the analytical solution decays.
The problem which you are trying to solve is a modification of this, although it really is quite an extensive and complicated modification because it involves separate domains, three dependent variables and interface conditions.
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I am doing a soil column experiment, using quartz sand as a transport medium. We are using 0.001 M NaNO3 as a background solution. Before injection to soil column the pH was adjusted to 7.5 with NaOH and HCl, but after sometime the pH of influent changes and the pH tends to decrease, so does the effluent. After this we used 0.0001 M NaHCO3 to stabilize the pH. The concentration of the influent becomes 0.0009 M NaNO3 + 0.0001M NaHCO3. but still it doesn't work and the pH of influent still tends to decrease. Please help me to solve this issue. I want to keep the pH at 7.5.
To maintain the pH at 7.5 you must use a buffer (a phosphate buffer can be used for this purpose). You have to check the buffer capacity to ensure that it can maintain the pH at the desired value.
I don't know the other details of your research, but I'm supposing the use of the buffer doesn't interfere with your experiments
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I am working on a project related to transport phenomenon in porous medium and I am required to calculate the saturation of the porous medium. Can I use the volumetric difference method to find out the saturation? Measuring the volume of fluid at inlet and outlet and then the difference in the volume is the amount of fluid trapped in the porous medium. Can I use this method?
Yes ofcourse , there are essentiallye two methods to obtain fluid saturations in porous medi. one is by X-raya and the other one is with using the volumetric method/material balance (the one you mentioned to). However, remember to account for the dead volumes and do pump flood at the end of your experiment to examine the impact of the capillary end effect so that you ensure that your data are accurate and reliable.
Regards
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Why does the imbibition process need a much higher pressure than the drainage process in the two-phase fluid flow in porous media?
Principally, because capillary pressure plays a positive role to drive the flow of wetting phase (e.g., water), the flow in an imbibition process (e.g., water displacing oil) should be easier (less pressure cost) than in a drainage (e.g., oil displacing water) process.
However, as shown by many laboratory core-scale test results, an imbibition usually needs a much higher pressure (e.g., 100 kPa) to drive the flow than a drainage (e.g., 20 kPa) under the same injection rate (e.g., 0.5 mL/min).
The high pressure during imbibition should be not due to the viscosity difference between fluids. When injecting either one of the phases alone in the media, the pressure drop is quite low.
I fully agree with previous answers. But your question is not clear enough.
the distribution of fluids (previous history) and wettability (if the viscosities are similiar) are the controlling factors for the pressure needed to flow. involving capillary pressure muddles the issue.
For example, if your water saturation is 40 % and all the other variables are the same. Not all the pores have 40%! some will have 100% and others 20%. Therefore, the pressure drop will be different for different pore size distributions, mainly if they are not unimodal.
Also, during imbibition and drainage at the same saturation you will have different fluid distributions and as a consequence different pressures.
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Hi y'all,
I was trying to push water through a piece of porous media. I was measuring the pressure drop of it under a constant flow rate, and saw that the pressure drop kept increasing over time.
It starts as ~1 psi, and increases to like 10 psi after 7 minutes
Does anyone know why? This only happens to one type of my samples.
Edit: this is an experiment. It keeps increasing, but I can’t measure accurately because my tunings start to leak after 12 psi
Hi Feichen and all.
OK: no loose particles migration and pore blocking. Then, the porous medium itself could be undergoing compression during experiment, thus reducing its permeability (Cf. Darcy’s Law). In this case, a constant flow rate would give what you getting: an increasing pressure drop. Try a constant very small flow rate. It will give a very small pressure drop, hopefully not enough to compress the medium and the pressure drop will be constant. If that is the case, you’re dealing with very compressible porous medium. If it is unavoidable to deal with this medium, for a given flow rate, you will need a large cross section so as to have low velocity and low pressure drop.
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Using a local thermal equilibrium model required that the averaged heat exchange between each phase of a porous medium is equal to zero. However, locally it could be very high. Effective conductivity will, thus depends on ratio of thermal conductivity and specific surface (exchange surface between each phases). It means that in a case of close thermal conductivity, the effective conductivity will not be the sum of separate phase effective thermal conductivity.
We have to remember about convective heat transfer in fluid phase as well - if LTE consists of a sum of NLTE equations, convective part concerning fluid remains in LTE equation - so as fluid flows through the foam, heat transfer between phases occurs, so yes, ratio of thermal conductivity have impact
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Hydrodesulfurization in packed beds takes place according to the following general reaction:
Sulfur Compound (ArS) + 2H2 --- H2S + Aromatic (Ar)
The kinetic rate is given by:
rHDS = (−KHDS) [ArS]^1.6 * [H2]^0.56 / (1+kad * [H2S]) [kmol/(kgs • s)]
The adsorption coefficient (kad = 50, 000 [m3/kmol]) does not depend on the temperature.
KHDS = 2.5•10^12 • exp(-19.384/Ta) [(m3)^2.16/(kg •(kmol)^1.16 • s)]
The geometry is a 3D cylinder and assembly meshing gives me a minimum orthogonal quality of 0.92, which is a desirable mesh. I have activated the Eulerian 2 phase and species transport models, and selected the mixture template for both the phases in the species transport model. Next in the materials section, all four materials (ArS, H2, Ar, and H2S) are defined inside the mixture template. The porous media is selected in the cell zone conditions and the appropriate UDF is loaded for the same.
Following this step I have attempted two different ways to execute the simulation:
1. Selecting mixture template for both gas and liquid phases and defining the materials in the same. Then, defining the reaction by defining the stoichiometric coefficients in the mixture template in the materials section. The following UDF for the reaction rate taken from the ANSYS manual was modified according to my reaction and defined and loaded as a function hook:
#include "udf.h"
#include "mem.h"
#define KHDS 0.005083992078
DEFINE_VR_RATE(vol_reac_rate,c,t,r,mole_weight,species_mf,rate,rr_t)
{
begin_c_loop(c,t)
{
real X_ars=C_YI(c,t,3)*C_R(c,t);
real X_h2=C_YI(c,t,1)*C_R(c,t);
real X_h2s=C_YI(c,t,0)*C_R(c,t);
else
*rate = 0;
*rr_t = *rate;
}
end_c_loop(c,t)
}
2. Selecting two different templates to define the materials and following the remaining steps as it was in point no. 1.
I am using ANSYS Fluent for the simulations and maintaining a time step size of 1e-08, but there is no change in the mass fraction of the reactants. In other words the mass fractions of ArS and H2 are 1.0 throughout the simulation and mass fractions of Ar and H2S are 0.
Any kind of support regarding this would be reallyhelpful.
Thanks.
Performing calculations with the assumption of plug flow and additionally assuming that the process takes place in one phase - the gas phase, will allow you easily to test the kinetic equation. The mass balance equation will take the form:
ArS/dz = (mc/(FovcArSo)) rArSArS), αArS(0) = 0,
where αArS - conversion of ArS, z = m/mc, mc - total mass of catalyst, FoV - volumetric flow rate, cArSo - initial concentration of ArS.
It is necessary to know the values of cArSo, cH2o, FoV, mc and temperature for calculations. It is also necessary to specify the stoichiometric equation (in particular, the number of hydrogen moles), because without this the stoichiometric analysis will be impossible. Regards,
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For a given porous medium with known porosity, particle size and other necessary material properties, how can I arrive at an equation which would express the time required for the given porous medium to fully saturate? The fluid properties and flow conditions (flow rate, pressure drop, etc.) are known. Can I express Darcy's equation as a time-dependent equation?
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Dear Researchers,
I am now working on the development of modeling EOR project. However, I am stuck with the method to simulate flow diversion mechanism created by polymer flood that reduce high permeability zone. The flow then will sweep into small permeability area.
One solution I found was using Dynamic Permeability Model. Which is not possible to be created in CMG or other reservoir simulation.
Thanks
Industrial grade reservoir simulators like IMEX/ECLIPSE/INTERSECT/... are probably unsuited for the type of work you want to perform. You likely need to access and tweak the physical engine of the simulator. R&D codes are what you are looking for. Some source code, which allows you to tweak physics at core, are open source. Google MRST, ADGPRS, OPENFOAM, etc. I would expect some tweaks to be already available in those codes. This will require some investment on your side into the selected code. It is probably advisable that you select one that is used by people around you.
A very crude alternative is to tweak an industrial grade simulator with restarts or use some of the options that exist in some of those "a little bit far". But this is very crude and messy, I would not recommend that.
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I need some literature about transport of Phosphorus in soil porous media.
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What are the steps required to solve numerically the phenomena of turbulent natural convection in porous media?
Sincerely, dear friends
The steps required to solve numerically the phenomena of turbulent natural convection in porous media are:
1- Define your physical case shape
4- Identify Boundary Conditions
5- Select a software to solve your governing equations with identified boundary conditions
6- Or Solve your system of equations by Fortran or similar
7- Expect your results and sole for Outputs like Velocity distribution, temperature distribution, Dimensionless Numbers relations, ........
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Phosphate nanoparticles
Dear Tufail, please find enclosed some of the literature on your desire subject. Beside this, you may also read some of my publication on biosynthesis of phosphorus nano-particles and its effect on crop plants may be available under research gate.
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Hi everybody,
Both of groundwater modeling system(GMS) and surface water modeling system(SMS) are well known.
Is it possible link them to evaluate flow exchange and pollution transport in river-aquifer interactions?
Which two software do you recommend for this purpose?
You can link them using "FREEWAT" open source platform based on QGIS. There are many detailed tutorials ! It's free and only you must to register for downloading!
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in the small diameters (or depth for rectangular one) the trickle flow can't be exist. am I right? what is the threshold?
Hi Stainstaw Anweiler,
I want to make a trickle regime that gas and liquid simultaneously flow through a soild porous medium and the problem is with making the physical flow. I read some papers about trickle flow and the minimum depth that i found was about 3cm for rectangular cross section and in one paper the *hydraulic* diameter for an annulus bed was 2cm. for the most 2D beds, depth was smaller than 1cm. but i don't want a 2D bed.
I will be happy if it's possible to make a rectangular cross section trickle bed with 1.4cm depth.
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The problem physics involves leakage past calibrated orifices of the piston , which is a moving boundary. In addition , the fluid is magnetisable, i.e MR Fluid .and its apparent viscosity can be varied in realtime. So the need is to model and solve for the behaviour in terms of Shear force developed or the apparent viscosity change with change in magnetisation,
A new present of ANSYS is the model of Magnetic Field Data and you can add that data in Fluent.
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Two-phase flow without the presence of porous media are traditionally solved by the Volume of Fluid (VOF)-like methods.
Dear Omar Rafae Alomar,
I learnt VOF from the following papers/chapters:
(1) Volume of Fluid (VOF) Method for the Dynamics of Free Boundary by Hirt and Nichols (1981)
(2) Volume-Tracking Methods for Interfacial Flow Calculations by M. Rudman (1997)
(3) Time-Dependent Multi-material Flow with Large Fluid Distortion by D. L. Youngs (1982)
(4) A new volume of fluid advection algorithm: The defined donating region scheme by Harvie and Fletcher (2001)
(5) A geometrical area-preserving Volume-of-Fluid advection method by Aulisa et al. (2002)
(6) Second-order accurate volume-of-fluid algorithms for tracking interfaces by Pilliod and Puckett (1997)
(7) A New Volume of Fluid Advection Algorithm: The Stream Scheme by Harvie and Fletcher (2000)
(8) Conservative Volume-of-Fluid method for free-surface simulations on Cartesian-grids by Weymouth and Yue (2010)
(9) Reconstructing Volume Tracking by Rider and Kothe (1999)
and I (dare) list my own article as the tenth entry :)
(10) A redistribution-based volume-preserving PLIC-VOF technique by Saincher and Banerjee (2015)
The following book will also prove to be helpful...
Computational Methods for Multiphase Flow. By A. Prosperetti & G. Tryggvason (I have attached a link to the book's webpage at Cambridge)
Regarding you question about the best reference...I do not think there exists an article/chapter that is self-contained in terms of all the information that is required to implement a VOF-algorithm...the above articles/chapters complement each other in terms of necessary information and thus should be read in conjunction.
Best regards,
Shaswat Saincher
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I would want to investigate some multiphase flow parameters (pressure gradient, liquid holdup among others) of some oil wells and compare them with results of some commercial software using the the various flow models - Beggs and Brill, Asari et al.,
I would like to analyse the heat transfer in the wells as well.
i would be grateful for matlab codes to help me with my analyses
Instead of searching for MATLAB codes, I think it is advisable to study Wellflo design and analysis software. This will help you with the basics on how to develop your own unique MATLAB code.
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hi, i am trying to understand why the porosity is included in several models of mass transfer in porous media and in other models is not included
Especially you Michael.
Greetings,
Jaime
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I am looking for the following properties of Thermoplastic Elastomers or TPE like materials:
1.Flow resistivity (Pa.s/m^2)
2.Porosity
3.Tortuosity factor
Will also like to know from experts alternative ways to simulate the sound Transmission Loss of acoustic plugs made of TPEs.
Best Regards,
David
Hi David
I am guessing that you can use micro models to design at least some of the properties. That said, you would need physical measurement to verify the end result or, at least, measurement would be a prudent step to secure the end result.
Have fun
Claes
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At present I'm having difficulties in making the solid particles flow inside the channel.
So can anyone give some inputs on this?
you need to go for the stable suspension with a lesser concentration.
Which type of suspension you are preparing??
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I have a coupled darcy flow and heat transfer in porous media module in COMSOL.
I would like to independently know the temperature of the fluid and temperature of the porous medium separately, however I see only one temperature. Does anyone know how to incorporate 2 temperatures?
The same has been raised in a COMSOL thread also.
Given that the question was in 2014, this answer may now be superfluous....
I agree with Prof Dong Chen - you need to have two different heat transport equations, one for the solid phase and one for the fluid phase. This is known as Local Thermal NonEquilibrium (LTNE), and is now well-studied.
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Hello everybody,
I have a question in solving a fully developed porous tube. As we know, porous equations are under volume averaging in an r.e.v. So, because of using averaged amount of velocities, is it ok to consider axisymmetric boundary condition in the center of pipe?
thanks a lot.
Good luck!
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Hello.
I am working on a micro scale simulation of evaporation inside a porous structure, using ANSYS FLUENT. It is a transient two phase model(VOF) considering water and vapor inside a micro scale pore. I am using UDF codes to apply the source terms relative to the mass transfer according to Schrage's model formulation.
The results that I get seem to be logical, but my problem is that the time steps that I have to use are very small ( in the order of ~1e-9 s), which make it impossible to reach convergence.
Every time I increase the time step, I face the error that the "Global Courant number is greater than 250.00. The velocity field is diverging. check the solution and reduce the time step".
I really appreciate it if you have any suggestions or solutions for this problem or you have any recommendations for me to increase the time steps to more realistic values.
In my opinion you must go with VOF HRIC model to carry out your simulation
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What type of contacts do we need to use for interface between fluids and solid ?
(For Fluent)
Normally, you can get quick results with the no slip boundary. You can also set it as wetted wall but you have to know the contact angle of the fluid on the solid.
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hi every body i need your help to model a deform-able solid that amount of air trapped in it and then a force is applied on the boundary of solid ...
thanks
thanks so much man ...
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Recently i have been trying to solve such a problem: how to couple free flow and Darcy flow for two phase fluid by Comsol in other to simulate the real situation of fluid flow freely near the permeable wall. I tryed to simulate the free flow (between two planes or in a pipe, etc) by phase field model and Darcy flow by two phase Darcy model. In the interface of the two models, we have to set three conditions: (1)tangential stress by using Beavior-Joseph-Saffman(BJS) boundary condition; (2)equal pressure; (3)equal velocity field. We can add the BJS condition by correcting the weak expression of Inlet pressure, no viscous stress. But how to constrain the equal pressure and velocity? By weak constraint, too? And how to solve the coulpling models is another problem. I want to solve it segregatedly. First solve the phase field model with the pressure constraint in the interface to get all other parameters like velocity and phase field variale. Then use the velocity obtained as the interface condition of Darcy model and to solve Darcy model to get a new pressure. Then go back to the first step to get the solution of the next time step. I know segregated solver will be a good choice. But does it solve the problem as the above sequence? I don't understand this solver's real theory. Thanks a lot if anyone can help me! It has perplexed me so long.
I did not use the method you said since I would like to carry out two phases flow, and brinkman equation is not available for two phases, this has been proved, thanks@Mohammad Ghalambaz
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Let us consider a periodic box filled with a fluid. There are solid fixed inclusions in the box. The Reynolds number is low and the Stokes equations apply. A space varying but time invariant volume force drives the fluid. What conditions must the volume force satisfy so that the flow rate across the box is zero in permanent regime ?
if you have a body inside the box, the equilibrium prescribes that the surface integral of  the pressure balances the integral of the stresses...
Assuming Int [V] v dV = 0 at any time, you have from integration of the momentum (fixed and non-permeable walls), remembering that Grad p = Div (pI)
Int [t0,t] dt ( Int[S]  n p - n. 2mu Grad v dS) =0
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The routine and classical reservoir engineering divides the composite systems as either parallel, series, or a mix of both cases. In these systems, the overall systems permeability and porosity will be determined by writing the Darcy's law equation for each layer and equating either the flow rate (in series systems) or overall pressure drop (in parallel systems). However, this is not the case when the interface between layers is inclined or curved. An example is shown in the attached file.
I appreciate receiving any suggestion that helps calculating average porosity and permeability for this system.
Dear Sir,
Regards
Dominique
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I am a PhD candidate trying to use DE-LBM for modeling the behavior of a porous media (sandy soil for instance) subjected to fluid flow. I just started to understand the fundamentals of LBM. Is the LBM formulation independent of the coefficient of permeability (k)?
Hello,
Please read this article : Quantitative analysis of numerical estimates for the permeability of porous media from lattice-Boltzmann simulations by Ariel Narvaez (doi:10.1088/1742-5468/2010/11/P11026)
There's a link between the viscosity and the boundary conditions, which may be reduced when the MRT algorithm is used.
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During a compaction of bitumen emulsion-based materials for pavement structural layers, and after it is finished, free water is released as a consequence of emulsion breaking. Thereafter, water steadily migrates through porous media of the specimen and evaporates outside specimen. Depending form the environmental conditions, this process takes place for weeks. I am looking for non-destructive methods to study the process of transport and evaporation of that water over time.
Dear Miomir,
For humidity in asphalt only have experience with neutron backscatter measurement. Troxler portable gauges for field measurement.
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I am modeling Bubble array acting as impact reduction liners, where bubble contains fluid in it. So, I am using hydrostatic element inside the bubble. What should be the element type I should use to mesh the bubbles?
Thank you
If you are using abaqus, I suggest using for 3D analysis C3D8 and for 2D analysys CPS4. You also can use C3D8R and CPS4R with reasonable accuracy and less computational demand.
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I have CT images of metal foam and was able to import it to ICEM CFD as '.STL ' file and mesh the solid part.
I want to create a domain enclosing the solid part with void spaced occupied by fluid, for this I have separate solid and fluid part.
Even though currently I am able to identify solid part and name it as a single part, same is not possible with fluid domain.
How can I identify the void space as a part, so that subsequent meshing of these part could be done?
After X-ray tomography you have the freedom to select (by masking) your different density domain from histogram by selecting/specifying the grey values. In the present case I believe that you have 2 phases. Solid and air(open void)can be separated individually and simultaneously from the histogram. It is available in image processing softwares like scanip(pretty much sure) and in volumegraphics. After masking you have option to mesh your solid and air domain separately.
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Dear researchers,
I am interested with the research of the simultaneous visualization and pressure-drop measurement of the two-phase flow in transparent channels. I am looking for cooperation with scientists who correlated gas-solids or gas-liquids flow imaging with different quantitative features, such as:
a)      pressure drop values along the channel;
b)      heat transfer values of the process;
c)       the reaction speed value inside the channel;
d)      etc...
I tried to simply illustrate the problem in the attached image.
I have developed interesting analytical methods for qualitative and quantitative correlation research on two-phase flow dynamics, and I am interested in cooperation.
Best regards.