[iam]

Hi,

I am trying to simulate in fluent a porous burner, how could I estimate Rv and Ri?
The porosity is not caused by particles, but by a fiber shaped medium, so I assume I cannot use Ergun's equation.

Thanks!!

[alexblue]

Dear all,

I try to create an channel--chamber--channel device. Let the water flow through a porous media and measure the pressure drops between inlet and outlet. but now I meet a problem that I don't know how to evaluate the resistance of the porous matrix. The pores of matrix is made by foaming, not by particles. So I think the Ergun equation dosen't apply on it.

Is there a model for calculating resistance of matrix like this?

Thanks in advance

[annu]

Originally Posted by A CFD free user

Hi
you're welcome. Yes, my main focus is porous media in PEM fuel cell, and catalytic reactions.

hey there, i am working on catalytic reaction in FBR. I don't understand how to incorporate reaction in the porous media, Can you please help me? I am badly stuck and Fluent manual doesn't seems to help me. Please revert

Thank you

[ssc_]

Originally Posted by srjp

The viscous and inertial resistances to flow in a porous medium can be calculated from the Ergun equation, which gives the total pressure drop through a porous medium.
Check any book on fluid mechanics for the Ergun equation
Total pressure drop = Viscous loss + inertial loss

dp/dl = [150*mu*(1-e)^2/phi^2*D^2*e^3]*v + [1.75*rho*(1-e)/phi*D*e^3]*v^2

The first term is the viscous loss (proportional to velocity) and the second term is the inertial loss (proportional to velocity squared).

Compare this to the Fluent's expression for momentum sink:

dp/dl = Rv*mu*v + (Ri/2)*rho*v^2

This gives the values for Rv and Ri,


Rv = [150*(1-e)^2/phi^2*D^2*e^3]


Ri = [2*1.75*(1-e)/phi*D*e^3]


Nomenclature:
Rv: Viscous resistance
Ri: Inertial resistance
mu: Viscosity
rho: Density
e: Porosity of the medium
phi: Sphericity of the particles making the medium (can assume 0.75)
D: Diameter of particles making the medium
v: Average velocity

Good Morning

I am trying to simulate the flow of two air-water phases in a porous medium. I am using VOF in ANSYS. Some of the inputs for the model are the viscous resistance and the inertial resistance, this for both fluids (air-water). I can not extract these two data from a laboratory test. I see that the user srjp makes an excellent contribution on the subject, as I understand we can calculate both data only with the porosity of the medium (e), sphericity (phi) of the particle and the diameter (D) of particle making the medium.

Since the simplified equations include only parameters related to the porous medium and not to the fluids, how could the situation be handled? That is, both air and water could handle the same values ​​of viscous resistance and inertial resistance. Someone could recommend me something to do or some relationship that exists or normally the air has a pressure drop related to the value of the water in the same porous media. I am new in this research topic and you excuse me if I have any error in the way of understanding the situation.

Regards,

[acalado]

The equation is not independent of fluids, as it has both the dynamic viscosity (mu) in the firs term, and density (rho) in the second/inertial term.

You could try and use the appropriate values for each fluid, but since you have both of them interacting and flowing through the porous medium my guess is the pressure drop will not be just a linear interaction of the two of them and will be highly dependent on the interaction between fluids.

[ssc_]

Originally Posted by acalado

The equation is not independent of fluids, as it has both the dynamic viscosity (mu) in the firs term, and density (rho) in the second/inertial term.

You could try and use the appropriate values for each fluid, but since you have both of them interacting and flowing through the porous medium my guess is the pressure drop will not be just a linear interaction of the two of them and will be highly dependent on the interaction between fluids.

Hello, thanks for the attention.

When I am mentioning that the equations do not depend on the fluid, I am referring to these:

Rv = [150 * (1-e) ^ 2 / phi ^ 2 * D ^ 2 * e ^ 3]


Ri = [2 * 1.75 * (1-e) / phi * D * e ^ 3]

Nomenclature:

Rv: Viscousresistance
Ri: Inertial resistance

It would be of great help to me if you provide me with some reference where I can find the appropriate values for each water-air fluid.

Regards,

[A CFD free user]

Originally Posted by iam

Hi,

I am trying to simulate in fluent a porous burner, how could I estimate Rv and Ri?
The porosity is not caused by particles, but by a fiber shaped medium, so I assume I cannot use Ergun's equation.

Thanks!!

There are several correlations in the literature to calculate the pressure drop in the foam-based media, e.g. Spielman and Goren is used for calculating of pressure drop in filter media.

[elnaz khodadadi]

Hi everyone
I am trying to model reduction of fouling in ultrafiltration module with fluent,for detemining Viscous and inetial resistance coefficients , can i use these formulas? also i want to use multiphase model because i have clay solution(clay+water)as a feed
best regard

[Arsalan_kh]

Hello
Nowadays I'm just working on modeling the heat transfer in a channel using porous media with a constant wall temperature.
First of all, I'm validating an article before starting my project. In the article, it has mentioned the inertial parameter and inertial coefficient of porous media by these equations:
AE= (CE*H*e)/[(K)^(0.5)]
CE=(1.75*e)/[(150*(e^5))^(0.5)]

AE=inertial parameter
CE=inertial coefficient of porous media
H=channel height(m)
e=porosity
K=permeability of the porous medium (m^2)

The value of AE=16.5 and H=1 and e=0.75 and K=10^(-4) has been considered.

This is my question. How can I add inertial parameter in porous zone area in the fluent?

( Fluent -> Cell Zone Conditions -> porous zone area )

Thanks.

[Goenitz]

Originally Posted by Arsalan_kh

Hello
Nowadays I'm just working on modeling the heat transfer in a channel using porous media with a constant wall temperature.
First of all, I'm validating an article before starting my project. In the article, it has mentioned the inertial parameter and inertial coefficient of porous media by these equations:
AE= (CE*H*e)/[(K)^(0.5)]
CE=(1.75*e)/[(150*(e^5))^(0.5)]

AE=inertial parameter
CE=inertial coefficient of porous media
H=channel height(m)
e=porosity
K=permeability of the porous medium (m^2)

The value of AE=16.5 and H=1 and e=0.75 and K=10^(-4) has been considered.

This is my question. How can I add inertial parameter in porous zone area in the fluent?

( Fluent -> Cell Zone Conditions -> porous zone area )

Thanks.

Hi man,

I cannot help you as I am new to porous-fluid interaction but may I ask what is your end goal? As I am also doing same thing i.e porous medium effect on fluid flow heat transfer in reactor channels. I am using CFX btw. My main ref article is by Abdelhakim Settar

[mohkh]

Dear All
help
How to calculate the inertial resistance when using porous media to simulate blood flow.
I can not find a way to calculate the inertial resistance. if somebody knows a way to solve it. and is it necessary to calculate it?
best regards