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

How to model porous jumps

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 28, 2008, 07:53
Default Hello everyone, I'm student a
  #1
mat
New Member
 
Martin Brinks
Join Date: Mar 2009
Location: Aachen, Germany
Posts: 5
Rep Power: 7
mat is on a distinguished road
Hello everyone,
I'm student apprentice and my task is to try some test cases in OpenFOAM for my company and to compare that with Fluent.
Now I have a test case, which i can not solve by myself, maybe you can help me. I have already simulated some perforated sheets to get the pressure loss and the drag coefficient. I shall now replace the perforated sheet with a porous jump condition. This worked well in Fluent, but I do not know how to do a porous jump in OpenFOAM. I already know that there are no interior faces in OpenFOAM and build a geometry which has a split at the location where I want the porous jump to be. But I could not find a boundary condition for OpenFOAM which simulates a cyclic condition and a pressure drop. Is there such a condition? Or can I solve that problem in a different way (maybe with a porous zone) ?

Regards,

Martin
mat is offline   Reply With Quote

Old   October 29, 2008, 10:35
Default Hi Martin, for starters che
  #2
Member
 
Ville Tossavainen
Join Date: Mar 2009
Location: Helsinki, Finland
Posts: 60
Rep Power: 7
villet is on a distinguished road
Hi Martin,

for starters check out the tutorial cases for "rhoPorousSimpleFoam" and the source code. The present method corresponds to the Fluent's "porous zone" model (volume). Jasak mentioned some months ago about his "porous jump" implementation which is based on cyclic BC. Search forum for that.

If you import the mesh from Fluent's preprocessor, make sure you have defined a separate porous volume. The name should match to the name mentioned in "/constant/porousZones" dictionary. Only Darcy's law is mentioned in the dictionary in the example case, but you can also define the porosity by exponential constants. Those should be the only changes compared to running with "rhoSimpleFoam". Making your own porous solver for incompressible flows is quite straightforward.

Hope this helps you!

Ville
villet is offline   Reply With Quote

Old   October 30, 2008, 05:45
Default Hi Ville, first, thanks for
  #3
mat
New Member
 
Martin Brinks
Join Date: Mar 2009
Location: Aachen, Germany
Posts: 5
Rep Power: 7
mat is on a distinguished road
Hi Ville,

first, thanks for your help, I started setting up a case for a porous zone with rhoPorousSimpleFoam. For the mesh, I did not define a porous volume in the preprocessor. After the mesh conversion I used cellSet to define a set and then used setsToZones. I guess that is equivalent.
I get an error, I suppose I forgot a value in one of the dictionarys. If you need files, I can post them here or send them to your mail address.

Here is the output:
/*---------------------------------------------------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.5 |
| \ / A nd | Web: http://www.OpenFOAM.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/
Exec : /usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimpl eFoam
Date : Oct 30 2008
Time : 10:43:20
Host : wum
PID : 19079
Case : /data/Projekte/Intern/Test_OpenFOAM/Vergleich_Fluent-OpenFOAM/Blech_30_630x630_e in_Blech/porousJump
nProcs : 1

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Reading thermophysical properties

Selecting thermodynamics package hThermo<puremixture<consttransport<speciethermo<hc onstthermo<perfectgas>>>>>
Reading field U

Reading/calculating face flux field phi

Creating turbulence model

Selecting RAS turbulence model realizableKE
realizableKECoeffs
{
Cmu 0.09;
A0 4;
C2 1.9;
alphak 1;
alphaEps 0.833333;
alphah 1;
}


Starting time loop

Time = 1

DILUPBiCG: Solving for Ux, Initial residual = 0.99909, Final residual = 0.040439, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.999011, Final residual = 0.0435777, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.0673226, No Iterations 1
#0 Foam::error::printStack(Foam:stream&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib/libc.so.6"
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 void Foam::divide<foam::fvspatchfield,>(Foam::Geometric Field<double,>&, Foam::GeometricField<double,> const&, Foam::GeometricField<double,> const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#5 Foam::tmp<foam::geometricfield<double,> > Foam::operator/<foam::fvspatchfield,>(Foam::GeometricField<double ,> const&, Foam::tmp<foam::geometricfield<double,> > const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#6 main in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#7 __libc_start_main in "/lib/libc.so.6"
#8 Foam::regIOobject::readIfModified() in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
Floating point exception

Martin
mat is offline   Reply With Quote

Old   October 31, 2008, 15:11
Default I think you have used the righ
  #4
Member
 
Ville Tossavainen
Join Date: Mar 2009
Location: Helsinki, Finland
Posts: 60
Rep Power: 7
villet is on a distinguished road
I think you have used the right utilities. I'm not sure if I'm that much of help, but you can send the files here so someone else can also help you.

Have you tried to run your case first without porous media using "rhoSimpleFoam" solver? I was thinking you have used zero values (instead of absolute pressure e.g. 1e5) in "/0/p"-file?
villet is offline   Reply With Quote

Old   November 4, 2008, 02:54
Default Hi Ville, actually, you are
  #5
mat
New Member
 
Martin Brinks
Join Date: Mar 2009
Location: Aachen, Germany
Posts: 5
Rep Power: 7
mat is on a distinguished road
Hi Ville,

actually, you are very helpful, because I have used zero pressure. Now when using absolute pressure, the computation works.
Thank you very much.

Martin
mat is offline   Reply With Quote

Old   November 4, 2008, 09:27
Default I have made the same mistake f
  #6
Member
 
Ville Tossavainen
Join Date: Mar 2009
Location: Helsinki, Finland
Posts: 60
Rep Power: 7
villet is on a distinguished road
I have made the same mistake for several times
villet is offline   Reply With Quote

Old   November 5, 2008, 02:37
Default Hello, I have another probl
  #7
mat
New Member
 
Martin Brinks
Join Date: Mar 2009
Location: Aachen, Germany
Posts: 5
Rep Power: 7
mat is on a distinguished road
Hello,

I have another problem: For some reason I don't seem to have an inflow. I'm using the flowRateInletVelocity. Here is my inlet:

inlet
{
type flowRateInletVelocity;
flowRate 0.04;
value uniform (0 0 0);
}

even if I use higher values for flowRate I still get a very low velocity, which is likely to be introduced by temperature gradients.
In the forum I read that the "value" entry is a dummy and it's ok to set it zero.
Do you know what's my mistake here?

Martin
mat is offline   Reply With Quote

Old   November 5, 2008, 10:44
Default Hey, forget the post above,
  #8
mat
New Member
 
Martin Brinks
Join Date: Mar 2009
Location: Aachen, Germany
Posts: 5
Rep Power: 7
mat is on a distinguished road
Hey,

forget the post above, I seem to be unable to change files properly.

But I have another question: I'm also simulating a compressible flow with heat conduction. But I don't find a way to enter the heat conductivity of my material. The simulations I have done so far overestimate the conduction. How can I lower the heat conductivity?

Thanks,
Martin
mat is offline   Reply With Quote

Old   April 17, 2013, 04:34
Default cellset
  #9
New Member
 
hesam
Join Date: Mar 2013
Posts: 13
Rep Power: 3
hesamgh is on a distinguished road
hi
i'm beginer in of
would you mind please explain me how can i separate the porous zone?
i convert my face from gambit to of, but the of did not recognize my porous media and all the faces ?!!

thanks

Quote:
Originally Posted by mat View Post
Hi Ville,

first, thanks for your help, I started setting up a case for a porous zone with rhoPorousSimpleFoam. For the mesh, I did not define a porous volume in the preprocessor. After the mesh conversion I used cellSet to define a set and then used setsToZones. I guess that is equivalent.
I get an error, I suppose I forgot a value in one of the dictionarys. If you need files, I can post them here or send them to your mail address.

Here is the output:
/*---------------------------------------------------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.5 |
| \ / A nd | Web: http://www.OpenFOAM.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/
Exec : /usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimpl eFoam
Date : Oct 30 2008
Time : 10:43:20
Host : wum
PID : 19079
Case : /data/Projekte/Intern/Test_OpenFOAM/Vergleich_Fluent-OpenFOAM/Blech_30_630x630_e in_Blech/porousJump
nProcs : 1

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Reading thermophysical properties

Selecting thermodynamics package hThermo<puremixture<consttransport<speciethermo<hc onstthermo<perfectgas>>>>>
Reading field U

Reading/calculating face flux field phi

Creating turbulence model

Selecting RAS turbulence model realizableKE
realizableKECoeffs
{
Cmu 0.09;
A0 4;
C2 1.9;
alphak 1;
alphaEps 0.833333;
alphah 1;
}


Starting time loop

Time = 1

DILUPBiCG: Solving for Ux, Initial residual = 0.99909, Final residual = 0.040439, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.999011, Final residual = 0.0435777, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.0673226, No Iterations 1
#0 Foam::error:rintStack(Foam:stream&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib/libc.so.6"
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 void Foam::divide<foam::fvspatchfield,>(Foam::Geometric Field<double,>&, Foam::GeometricField<double,> const&, Foam::GeometricField<double,> const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#5 Foam::tmp<foam::geometricfield<double,> > Foam:perator/<foam::fvspatchfield,>(Foam::GeometricField<double ,> const&, Foam::tmp<foam::geometricfield<double,> > const&) in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#6 main in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
#7 __libc_start_main in "/lib/libc.so.6"
#8 Foam::regIOobject::readIfModified() in "/usr/local/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/rhoPorousSimp leFoam"
Floating point exception

Martin
hesamgh 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
Porous model jack FLUENT 2 August 11, 2008 04:16
Velocity jumps - cont. momentum_waves Main CFD Forum 8 August 31, 2007 15:26
measured pressure in the discharge pipe jumps Jan Main CFD Forum 1 October 30, 2006 07:54
Will jumps of mesh size in FEM cause troubles? tang Main CFD Forum 0 June 19, 2003 10:59
How to use radiation model with porous model? jacky CFX 0 December 17, 2002 22:51


All times are GMT -4. The time now is 22:14.