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

Flow in porous media

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 7, 2005, 14:17
Default Flow in porous media
  #1
Anitha
Guest
 
Posts: n/a
Hi all,

I have a cylinder, open to atmosphere, consisting of two layers of different porous media each.Water flows in the cylinder at a very low rate. The viscous resistances in the two layers are such that one is 10^4 times the other.In the velocity contours,I expect to see higher velocity in the layer with less viscous resistance.But in the contours I see that velocity in the cylinder is same throughout.

I give velocity-inlet B.C. for the top face, pressure-oulet B.C. for the bottom face and wall B.C. for the side of the cylinder.I enable porous zone option for each of the two layers

why is this happening? Any idea?

Anitha.
  Reply With Quote

Old   June 7, 2005, 16:03
Default Re: Flow in porous media
  #2
Prakash Verma
Guest
 
Posts: n/a
Use physical velocity formulation in solver settings. I think you have used Superficial velocity.

-Prakash
  Reply With Quote

Old   June 7, 2005, 18:51
Default Re: Flow in porous media
  #3
Anitha
Guest
 
Posts: n/a
Hi Prakash, I tried it, but of no use Its still giving same velocity throughout By the way do resistance coefficients affect the velocity?If so,how?

TIA Anitha
  Reply With Quote

Old   June 8, 2005, 00:38
Default Re: Flow in porous media
  #4
Prakash Verma
Guest
 
Posts: n/a
hi Anitha, yes resistance coefficients affect the velocity. You have to supply viscous and inertial resistance coefficients. note that viscous resistance coefficents is 1/alpha (You have to specify it) ==> lower the coefficient means higher the resistance which results in higher velocity. For more help read the manual to calculate these coefficients which depend on particle size.

hope it helps -Prakash
  Reply With Quote

Old   June 9, 2005, 07:33
Default Re: Flow in porous media
  #5
korni
Guest
 
Posts: n/a
Hi Anitha!

If you cylinder has only one diameter, then it's correct that the velocity is the same (at least if it has side walls) because of the continuity... same mass flow and flow surface - same velocity...

But the pressure drop will be higher in the area with the higher resistance...

check that..

sorry for my poor english!

korni
  Reply With Quote

Old   June 9, 2005, 12:22
Default Re: Flow in porous media
  #6
Thiyaga
Guest
 
Posts: n/a
Hi,

Go for pressure inlet and pressure outlet BC if u kno pressure drop. then u can c variable velocity. regards.. Thiyaga.
  Reply With Quote

Old   June 11, 2005, 05:22
Default Re: Flow in porous media
  #7
Sudheendra
Guest
 
Posts: n/a
hi Thiyaga,

As I have said earlier, my cylinder is placed in open space so that pressure at the inlet and pressure at the outlet is also the same i.e. 1 atm.Infact I have tried this out but there is no flow at all.

So I started giving velocity-inlet at the inlet (since I know the incoming flow-rate) and pressure outlet at the bottom

What do you say?

Regards, Anitha.
  Reply With Quote

Old   June 11, 2005, 05:23
Default Re: Flow in porous media
  #8
Anitha
Guest
 
Posts: n/a
hi Thiyaga,

As I have said earlier, my cylinder is placed in open space so that pressure at the inlet and pressure at the outlet is also the same i.e. 1 atm.Infact I have tried this out but there is no flow at all.

So I started giving velocity-inlet at the inlet (since I know the incoming flow-rate) and pressure outlet at the bottom

What do you say?

Regards, Anitha.
  Reply With Quote

Old   June 13, 2005, 12:56
Default Re: Flow in porous media
  #9
Thiyaga
Guest
 
Posts: n/a
Hi,

there should be some pressure gradient, then only flow will occur through the porous media, calculate the value of pressure drop with Darcy's eqn (6.19.5 of Fluent6.1 manual), i think u know the value of permeability and velocity.use P(inlet)=P(outlet)+del P. hope this would help. regards Thiyaga.
  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
Compressible flow through porous media? JoFFe CFX 2 November 1, 2010 05:50
no converge - for Low Re Porous media seepage flow lee CFX 3 August 31, 2007 01:12
Modeling porous media flow in prostar Nirmal Kumar Pathak CD-adapco 8 November 23, 2005 08:18
Flow resistance of porous media Desheng Kong Main CFD Forum 3 December 19, 2000 12:07


All times are GMT -4. The time now is 20:35.