CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

POROUS MATERIAL

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 7, 2005, 15:59
Default whats there to discretize???
  #21
Super Moderator
 
niklas's Avatar
 
Niklas Nordin
Join Date: Mar 2009
Location: Stockholm, Sweden
Posts: 693
Rep Power: 19
niklas will become famous soon enough
whats there to discretize???

I do not understand what the problem is.
niklas is offline   Reply With Quote

Old   November 15, 2005, 19:10
Default Hi guys thank you everybody fo
  #22
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 8
maritozzo is on a distinguished road
Hi guys thank you everybody for the help you gave me, Thank you Bernhard first, you always answered my questions even if my questions were quite silly.
I wrote the solver and it seems work, i have the loss of pressure in correspondance of the space occupied by the porous media... Here is the final form of the velocity equation:

tmp<fvvectormatrix> UEqn
(
fvm::div(phi, U)
+turbulence->divR(U)+nu*(G & U)
);

I did not changed anything in the rest of the solver leaving it as in the original form of SimpleFoam. may someone tell me if i should change something in the rest of the solver because of the adding of the new term in the velocity equation or I can leave as it is?
maritozzo is offline   Reply With Quote

Old   November 16, 2005, 11:04
Default think you can leave as it is
  #23
Member
 
VVqf
Join Date: Mar 2009
Location: Braunschweig
Posts: 66
Rep Power: 8
vvqf is on a distinguished road
think you can leave as it is.
But I don't understand "fluid through a porous media OUTSIDE it", does it make sense?
Could you explain a little bit?

Did get different G in each time directory?
vvqf is offline   Reply With Quote

Old   December 5, 2005, 16:26
Default Hi Muzio Grilli: Could you
  #24
Senior Member
 
Guoxiang
Join Date: Mar 2009
Posts: 109
Rep Power: 8
liugx212 is on a distinguished road
Hi Muzio Grilli:

Could you please paste your solver to here, And let us to study that how to solve porous question.

Thanks.
Guoxiang
liugx212 is offline   Reply With Quote

Old   December 23, 2005, 12:27
Default Hi everybody, Bernhard Gsch
  #25
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
Hi everybody,

Bernhard Gschaider wrote:

By Bernhard Gschaider on Thursday, October 20, 2005 - 10:22 am: Edit Post

Sorry. With "out-of-the-box" I meant "a solver available in the OF-distribution". You'll have to write a solver yourself.

One approach would be to simply extend an existing solver by adding Darcy as a source-term. In the Darcy-term there is a permeability/resistivity (whatever formulation you prefer). By using a field for that and specifying appropriate values for certain regions you can define porous/non-porous-zones.

My Question: How can I define different appropriatet values for different regions? What boundary conditions do I have to choose for the interface between the porous and non-porouszone?

bye nico
nico is offline   Reply With Quote

Old   January 5, 2006, 16:19
Default Muozo Grilli, please post crea
  #26
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
Muozo Grilli, please post created.H, createG.H, createNu.H -files?
Thanks
nico is offline   Reply With Quote

Old   January 10, 2006, 09:33
Default My createG utility is very slo
  #27
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 8
maritozzo is on a distinguished road
My createG utility is very slow..you'd better use the setFields utility which is very simple to use, you only have to create the setFieldsDict file which you can find in thedamBreak tutorial and specify the opposite vertices of the box or the center and radius of the sphere in which you want to define the G tensor is really simple
maritozzo is offline   Reply With Quote

Old   January 10, 2006, 12:35
Default The problem is, that it only w
  #28
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
The problem is, that it only works, when you use blockmesh. I create my meshes in gambit and then this way doesn't work. It would be a great help for me, if you send me your createG utility.

Thanks
Nico

email : nico.petry@gmx.de
nico is offline   Reply With Quote

Old   January 16, 2006, 13:07
Default Hi! I have directed permeabil
  #29
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
Hi!
I have directed permeabilities and therefore I define G as a volTensorField. My problem is, that fvm::SuSp(nu*G,U) doesn't work for volTensorFields and nu*(G & U) does not give the right solution.
I am not quite sure why.

Hope somebody can help me.

Thanks
nico is offline   Reply With Quote

Old   January 16, 2006, 14:02
Default Hi nico the second form nu*(G
  #30
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 8
maritozzo is on a distinguished road
Hi nico the second form nu*(G & U) is the right one. You are using simpleFoam so you must choose in the right way the relaxation factors in the fvSolution file because otherwise the process will diverge and the solution will not be right.
Try diminuishing the relaxation factors.
You have to monitor the residuals to see that convergence is achieved.
maritozzo is offline   Reply With Quote

Old   January 17, 2006, 03:36
Default Thanks. Is it possible to c
  #31
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
Thanks.

Is it possible to calculate the relaxion factors, that will bring the right solution? Or is the only possibility trying out?

bye Nico
nico is offline   Reply With Quote

Old   January 17, 2006, 03:38
Default sorry, i mean relaxation facto
  #32
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
sorry, i mean relaxation factor
nico is offline   Reply With Quote

Old   January 17, 2006, 15:02
Default The default values are 0.3 on
  #33
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 8
maritozzo is on a distinguished road
The default values are 0.3 on p an 0.7 on all the other variables. First you should tell me which is the shape of the G tensor you defined and which are the values you inserted.
Anyway try starting with 0.1 on p and 0.5 on the others.
Then you should also look at the relative tolerances, try starting with 0.01 on p and 0.1 on the others then after a certain number of iteration switch to zero on all the variables
maritozzo is offline   Reply With Quote

Old   January 17, 2006, 16:11
Default Hi Muzio: [30000 0 0 G=
  #34
Member
 
Nico Petry
Join Date: Mar 2009
Posts: 36
Rep Power: 8
nico is on a distinguished road
Hi Muzio:

[30000 0 0
G= 0 15000 0
0 0 30000]

Why shall I switch the relativ tolerances to zero. I don't understand the sence of it.

Thanks for taking time for my problems.

Nico
nico is offline   Reply With Quote

Old   February 6, 2006, 15:43
Default Hi, friends, Could you plea
  #35
Senior Member
 
Guoxiang
Join Date: Mar 2009
Posts: 109
Rep Power: 8
liugx212 is on a distinguished road
Hi, friends,

Could you please sand the creatG.h and creatNu.h to me to learn?

Thank you very much.

email: gliu@mix.wvu.edu
liugx212 is offline   Reply With Quote

Old   February 14, 2006, 11:37
Default Hello Muzio or someone else,
  #36
Member
 
Guido Adriaensen
Join Date: Mar 2009
Posts: 56
Rep Power: 8
guido_adriaensen is on a distinguished road
Hello Muzio or someone else,

Sorry to ask for the same files as well. :-) But could you be so kind to share the created.H, createG.H, createNu.H -files? Thanks.
If you can email it to guido.adriaensen@modesi.nl, I would be very gratefull, thanks again

Guido
guido_adriaensen is offline   Reply With Quote

Old   March 6, 2006, 06:11
Default Dear OpenFoamers, has anyon
  #37
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Dear OpenFoamers,
has anyone of you tried to simulate the unconfined seepage problem?
The governing equation is

grad(p)=-rho*nu*U/[K] + rho * [g]

where [K] is the hydraulic conductivity (variable tensor) and [g] the gravity acceleration vector.

Things are complicated by the fact that the phreatic level is not a-priori known, but is part of the solution (equilibrium condition at atmospheric pressure).
For example, the goundflow in the picture below


How the problem can be addressed? Is the customisation of interFoam the unique possibility?

Thanks
Michele.
michele is offline   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
non-isotropic porous material gmmh FLUENT 0 September 4, 2007 06:38
Error while setting up porous material. Kiddo CFX 1 October 10, 2005 10:42
porous material ioana CFX 2 March 10, 2005 08:52
model for porous material sleepinglily CFX 3 October 19, 2004 10:45
Material in Porous media Rajab Rajab FLUENT 3 July 4, 2003 13:42


All times are GMT -4. The time now is 02:42.