CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Porous Media models in commercial CFD

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 18, 2002, 13:30
Default Porous Media models in commercial CFD
  #1
Clif Upton
Guest
 
Posts: n/a
What porous model is in Fluent? We have been using another commercial CFD code with Brinkman model and it is pretty bad in many circumstances. Of the results it produces are 100% off!
  Reply With Quote

Old   April 19, 2002, 14:11
Default Re: Porous Media models in commercial CFD
  #2
Evan Rosenbaum
Guest
 
Posts: n/a
FLUENT uses an extra sink term on the momentum equation to account for the extra resistance. The sink term has the form: (mu x v / alpha) + (C2 x 1/2 x rho x abs(v) x v) where mu is viscosity, v is superficial velocity alpha is a permeability factor, C2 is an inertial resistance factor and rho is density.

We have benchmarked single-phase gas flow using this model and gotten decent results. It doesn't work for multiphase or phase change, because you are limited to single entries for alpha and C2.

It can also use a power-law function of the velocity magnitude, but I'm not very familiar with that approach.
  Reply With Quote

Old   April 21, 2002, 00:23
Default Re: Porous Media models in commercial CFD
  #3
Greg Perkins
Guest
 
Posts: n/a
You can easily write a udf to compute this term or use another term that you prefer. In this case, you can then use more complex relations since you don't need to rely on the assumptions used by Fluent.

Greg
  Reply With Quote

Old   April 22, 2002, 12:40
Default Re: Porous Media models in commercial CFD
  #4
Clif Upton
Guest
 
Posts: n/a
Thanks, Evan. What you described is the Brinkman's model. As I mentioned, I completely fails in some circumstances, such as when the inflow is very non-uniform and at an angle, while the media's resistance is not very high.
  Reply With Quote

Old   April 22, 2002, 12:41
Default Re: Porous Media models in commercial CFD
  #5
Clif Upton
Guest
 
Posts: n/a
Could you explain what's udf? thanks.
  Reply With Quote

Old   April 23, 2002, 14:56
Default Re: Porous Media models in commercial CFD
  #6
Erwin
Guest
 
Posts: n/a
Simple models like that will also fail when turbulence dependent phenomena like dispersion (thermal, species) become important. Porous media need a specific turbulence model below porosities of say 0.8 to account for the pseudo-vortices around particles and size limited interstitial vortices between particles.
  Reply With Quote

Old   April 24, 2002, 05:04
Default Re: Porous Media models in commercial CFD
  #7
Greg Perkins
Guest
 
Posts: n/a
Have you tried any in particular?

What about the granular model of Fluent4? It has some turbulence models for the mutliphase flow, but I'm not aware if they account for dispersion as you point out. Do you know?

Regards Greg
  Reply With Quote

Old   April 24, 2002, 11:48
Default Re: Porous Media models in commercial CFD
  #8
Erwin
Guest
 
Posts: n/a
I am very unfamiliar with Fluent 4, but I'd guess that in a granular model Fluent it is assumed that the solids also flow. So Fluent offers a primary and secondary turbulence option to account for that. Maybe there's a way to modify it for porous media flow, I dunno.

I have not yet tried other turbulence models, since in our cases dispersion effects etc. have not yet been important. I did find two literature articles describing such models:

1) Turbulence model for flow thorugh porous media - T.Matsuoka - Int. J. Heat Mass Transfer - Vol.39, No.13, pp2803-2809

2) A general two-equation macroscopic turbulence model for incompressible flow in porous media - B. Antohe - Int. J. Heat Mass Transfer - Vol.40, No.13, pp3013-3024
  Reply With Quote

Old   April 24, 2002, 21:49
Default Re: Porous Media models in commercial CFD
  #9
Greg Perkins
Guest
 
Posts: n/a
Thanks - you can turn off the solids flow in Fluent 4 if you like.

Greg
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to model granular flow through porous media Axius FLUENT 2 August 7, 2014 11:34
Modelling sound propagation through layered porous media nkinar Main CFD Forum 0 July 4, 2010 15:45
porous media: Fluent or Star-CD? Igor Main CFD Forum 0 December 5, 2002 16:16
user friendly cfd code waqar Main CFD Forum 19 August 18, 2000 17:31
CFD - Trends and Perspectives Jonas Larsson Main CFD Forum 16 August 7, 1998 17:27


All times are GMT -4. The time now is 22:21.