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

porous media

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 31, 2004, 15:00
Default porous media
  #1
Kurt Malinski
Guest
 
Posts: n/a
I have a question about a fluid flow problem in a porous media. I have a brick that has very small air gap openings. I am injecting a gas into this brick and the porosity of the brick allows the gas to flow through to the other side. I am wondering if there is a way to get the average velocity of the gas leaving the brick instead of the local gas velocity occuring inside the porous material. Using the momentum equation it states that the gas inside the brick will have high velocities, I am not interested in the high velocity inside the brick. I am interested in the lower average velocity exiting the brick wall. Is there a way to program fluent to find the average smaller velocity exiting the brick?
  Reply With Quote

Old   September 1, 2004, 11:17
Default Re: porous media
  #2
Evan Rosenbaum
Guest
 
Posts: n/a
By default, FLUENT perform porous media calculations using the superficial velocity, which is exactly what you seem to want. While actual velocities in the brick will be higher, the superficial velocity formulation doesn't calculate them.
  Reply With Quote

Old   September 10, 2004, 17:37
Default Re: porous media
  #3
Kurt Malinski
Guest
 
Posts: n/a
I am still not confident that we want to find the superficial velocity for this ceramic brick. First of all the openings are very very small.

If I understand this right we basically assume that the fluid is flowing inside a open box that is 100% open for instance. We calculate for example the velocity based on the the cons. of mass and momentum. We then define the parameters which give us a very high velocity exiting the material and just use the relation vphysical=vsuperficial/porosity to calculate the superficial velocity. It seems we are loosing a lot of information about what is taking place inside the material. How accurate is that assumption. If we try to solve for the physical velocity i'm afraid that our material is packed too tight and the mesh we create might not be enough to give us good results either. Could we assume the material is a packed bed. Under what criteria can we assume that? How do we calculated loss coefficients based on the superficial velocity techniques? I would appreciate advice on how to go about attacking this problem and what would probably give the most accurate results.
  Reply With Quote

Old   September 13, 2004, 12:31
Default Re: porous media
  #4
Evan Rosenbaum
Guest
 
Posts: n/a
You are losing a lot of information about what happend inside. THere is an option to use actual velocities in FLUENT 6, which I believe assumes uniform resistance properties in an given flow direction. It is still just a "black box" momentum sink term and should give the same results as the superficial velocity formulation. As for calcuating the loss coefficients, this is explained in the FLUENT User's Manual.
  Reply With Quote

Reply

Thread Tools
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 On
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 10:34
Porous media setup issues in Fluent Bernard Van FLUENT 22 June 6, 2014 05:52
Multiphase Porous Media Flow - Convergence Issues VT_Bromley FLUENT 5 March 23, 2011 11:38
species mass source in porous media ? PK FLUENT 0 February 16, 2007 12:12
porous media: Fluent or Star-CD? Igor Main CFD Forum 0 December 5, 2002 16:16


All times are GMT -4. The time now is 04:10.