# Porous zone boundary condition- help needed

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

 May 21, 2002, 18:19 Porous zone boundary condition- help needed #1 Shankar Guest   Posts: n/a In setting up the boundary conditions for a porous zone, we need to specify the direcion vectors, how do we do that and what does it mean physically.(Fluent Manual wasnt elaborative) Thanks to all. Shankar.

 May 22, 2002, 08:53 Re: Porous zone boundary condition- help needed #2 sharad Guest   Posts: n/a I also have the same problem from last 6/7 months, but could not found the solution. FLUENT engineers only can help. If you get it pl. let me know the solution. All the Best!!

 May 22, 2002, 12:51 Re: Porous zone boundary condition- help needed #3 Evan Rosenbaum Guest   Posts: n/a Shankar, I will assume you are using FLUENT 5.x and are referring to the Boundary Conditions input screen. The direction vectors are used if the porous medium has orthotropic hydraulic resistance properties AND if the coordinate system for specifying these resistance properties is not aliigned with the global coordinate system. If for example, the porous medium coordinate system is rotated 45 degrees from the global coordinate system, then you would specify the Direction 1 vector as X = 0.707, Y = 0, Z = 0.707. By default, the Direction 1 vector is aligned with the global X-axis and the Direction 2 vector is aligned with the global y-axis. You only need to change these settings if your porous medium doesn't align with the global axes correctly. H.Salimi likes this.

 May 22, 2002, 15:36 Re: Porous zone boundary condition- help needed #4 sharad Guest   Posts: n/a Hi Evan, Thanx for the reply. I want to simulate the turbulent flow in a channel, whose bed is porous(sand) and there is upward seepage through the bed along with a turbulent flow in the channel. I have the following questions... 1. Is it possible to simulate the laminar flow in the porous sand bed and turbulent flow above the bed at the interface simultaneuosly to get velocity and shear stress distributions? i.e. How to use porous media Boundary condition in this case? 2. How to set the boundary condition at the sand & water interface which will take into account the roughness of sand and the upward seepage velocity? Please help at the earliest. Thanks in advance. Sharad Dugad

 May 22, 2002, 18:20 Thanks #5 Shankar Guest   Posts: n/a Thanks a lot Evan. Shankar.

 May 22, 2002, 18:23 Re: Porous zone boundary condition- help needed #6 Shankar Guest   Posts: n/a Thanks a lot Sharad. Shankar.

 May 23, 2002, 13:00 Re: Porous zone boundary condition- help needed #7 Evan Rosenbaum Guest   Posts: n/a FLUENT can't do what you want. The porous medium is simply a fluid with and additional, possibly orthotropic, momentum sink term. Because the porous medium is a fluid and not a solid, you will not get proper shear stresses at the interface and you cannot include the effects of any surface roughness.

 May 23, 2002, 15:19 Re: Porous zone boundary condition- help needed #8 sharad Guest   Posts: n/a Hi Evan, If it is not possible with FLUENT, do you know if there is any alternative solution/other software which can do this? Is it not possible to treat the sand-water interface as solid surface with some porosity and make it a 'Velocity Inlet' B.C. there? Waiting for Reply. Thanks. Sharad Dugad

 May 31, 2002, 14:28 Re: Porous zone boundary condition- help needed #9 Amadou Sowe Guest   Posts: n/a Hi Sharad, I have not done this in any project yet, but it is something that you can try and see if it works. I will write refering to Fluent 4, fluent 6 might have the capability but I don't know. Turn on your Eulerian Granular Multiphase model, with a continuous primary phase and sand as your granular phase. Patch the void fraction for your granular phase in the part of your domain you have the sand. Under solve-> controls->Equations, deselect the granular phase, this means you have frozen your granular phase and only the primary phase is solved. This is just a suggestion that may or may not work. Let me know if it works.

 June 1, 2002, 10:31 Re: Porous zone boundary condition- help needed #10 Sharad Dugad Guest   Posts: n/a Hi Amadou, Thanx a lot for your reply. Could you please explain in detail step by step procedure to do what you suggested. I am using Fluent 5.5 & Gambit for grid generation. Waiting for your reply. Sharad Dugad

 June 3, 2002, 12:57 Re: Porous zone boundary condition- help needed #11 Amadou Sowe Guest   Posts: n/a Hi Sharad, When I have the time I will give you a step by step explanation of what to do in fluent 4. Regards, Amadou

 March 18, 2012, 15:48 porous Jump #12 New Member   Akim Faisal Join Date: Jan 2012 Posts: 18 Rep Power: 7 Hi, I am having problems with specifying the boundary condition of a bottom wall of a 3D rectangular channel as a "porous jump" . In GAMBIT I select Boundary type as "Porous Jump" however, when I import my mesh in FLUENT I receive an error stating that: "Cannot change porous to porous-jump because there is only one adjacent cell thread". I am not sure what that means, can anyone please help me with this case. Any suggestion is appreciated. Thanks, Akim

 March 22, 2012, 07:44 #13 Senior Member   Join Date: Mar 2009 Location: Indiana, US Posts: 185 Rep Power: 10 Hi Akim, This means that the boundary you are specifying as a porous jump is an exterior surface, a porous jump BC can only be specified to an interior surface Regards Luke

 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 peob OpenFOAM Running, Solving & CFD 3 February 3, 2017 11:54 Mansureh FLUENT 5 June 5, 2011 09:31 csvirume FLUENT 2 September 9, 2009 01:08 YY CFX 7 April 20, 2008 22:04 hani OpenFOAM Running, Solving & CFD 0 July 4, 2006 07:09

All times are GMT -4. The time now is 08:01.