[pvpnrao]

Dear All

I am trying to simulate flow through porous media in OpenFOAM. Based on the posts on this forum, I have successfully run the simulation, but I am finding it difficult to understand the mathematics. I referred to the report by

http://www.tfd.chalmers.se/~hani/kur...ukurReport.pdf

Yet, I am lacking clarity.

Here is my understanding:
We are adding a source term to the momentum equation. This source term vanishes in the fluid region. In porous region it penalizes the velocity so as to force a reduction in its value within the control volume.

Here is my question:
How is the penalization term forcing the reduction in velocity?

Can someone please explain it with an example of one time iteration for evaluating velocity in porous zone?

Thanks in advance

[Phicau]

Hi Narsimha,

basically, those drag forces take some momentum to account for the real geometry that you have disregarded (individual elements forming the porous medium).

I suggest that you read section 2.4 of my thesis for an extensive description of this procedure:

https://docs.google.com/viewer?a=v&p...TMxMjdhZGI0NjU

Best,

Pablo

[pvpnrao]

Dear Pablo

Thank you very much.

However, the document is in Spanish and I cannot understand Spanish.

Do you have an English version of your thesis. I tried to workout using google translate but that is not very convenient.

Also, there is no section 2.4 in the thesis.Did you mean section 2.3?

[Phicau]

Scroll down, English version is after the short Spanish one...

[pvpnrao]

Thank you very much Pablo.

I have one more question: In Turbulent flows drag is not just a linear combination of laminar drag and turbulent drag.

But Forchhiemer law states exactly the opposite.

I was wondering how the linear combination of laminar drag and turbulent drag is justified?

[pvpnrao]

Also, with Darcy-forcchiemer law we are adding a nonlinear velocity term to the right hand side of the momentum equation. Ideally, this must lead to several complications in-case we use the implicit schemes. But OpenFOAM handles implicit treatment without much difficulty.

Is there something I am missing? How is the non-linear term getting treated when we add Darcy-Forchiemer terms to the Momentum equation.

I am using PimpleFoam solver

[Phicau]

Hi Narsimha,

The friction terms are linear, nonlinear and added mass. Sure that the porous material induces a turbulence enhancement, that is why you need to add some closure terms to the volume-averaged turbulence model, check on the thesis.

All the drag coefficients are treated explicitly for simplicity, at least in my solver.

Best,

Pablo