# Flow in porous media

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

 June 7, 2005, 14:17 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.

 June 7, 2005, 16:03 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

 June 7, 2005, 18:51 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

 June 8, 2005, 00:38 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

 June 9, 2005, 07:33 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

 June 9, 2005, 12:22 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.

 June 11, 2005, 05:22 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.

 June 11, 2005, 05:23 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.

 June 13, 2005, 12:56 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.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Axius FLUENT 2 August 7, 2014 10:34 JoFFe CFX 2 November 1, 2010 05:50 lee CFX 3 August 31, 2007 01:12 Nirmal Kumar Pathak CD-adapco 8 November 23, 2005 08:18 Desheng Kong Main CFD Forum 3 December 19, 2000 12:07

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