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

Force function for laminar case with interDyMFoam

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 13, 2012, 18:43
Default Force function for laminar case with interDyMFoam
  #1
New Member
 
Claudio
Join Date: May 2010
Location: Boston, MA
Posts: 28
Rep Power: 15
Claudio is on a distinguished road
I tried to add the "force" function shown below to the sloshingTank2D case in the OpenFOAM tutorials.

Code:
    forces
    {
        type forces;
        functionObjectLibs ("libforces.so"); //Lib to load
        patches (walls); // change to your patch name
        rhoInf 998.2; //Reference density for fluid
        rhoName rho;
        pName p;
        UName U;
        CofR (0 0 0); //Origin for moment calculations
        outputControl  timeStep;
        outputInterval 1;
    }
But when I run it I get an error that says
Code:
[0] --> FOAM FATAL IO ERROR: 
[0] keyword nu is undefined in dictionary "/users/ccairoli/OpenFOAM_Test/tutorials/multiphase/interDyMFoam/ras/sloshingTank2D/processor0/constant/transportProperties"
[0] 
[0] file: /users/ccairoli/OpenFOAM_Test/tutorials/multiphase/interDyMFoam/ras/sloshingTank2D/processor0/constant/transportProperties from line 20 to line 32.
[0] 
[0]     From function dictionary::lookupEntry(const word&, bool, bool) const
[0]     in file db/dictionary/dictionary.C at line 400.
[0] 
FOAM parallel run exiting
[0]
If I comment the force function out it runs with no errors.

Am I using it the wrong function for a laminar case? I use the exact same function for a turbulent case and have no errors either.

Any help would be greatly appreciated.

Claudio

PS: I'm attaching the file if anybody would like to try to replicate the problem.
Attached Files
File Type: gz sloshingTank2D.tar.gz (4.2 KB, 1 views)
Claudio is offline   Reply With Quote

Old   August 14, 2012, 21:42
Default
  #2
Senior Member
 
kmooney's Avatar
 
Kyle Mooney
Join Date: Jul 2009
Location: San Francisco, CA USA
Posts: 323
Rep Power: 17
kmooney is on a distinguished road
Hi Claudio,

The function is complaining because its looking for a viscosity entry in the constant/transportProperties dictionary but its not finding it. Unfortunately just adding this in will remove the error but give you the wrong results.

Because this is a multiphase simulation you have more than one viscosity to worry about and just handing some value will result in incorrect force calculations on the boundaries.

I'm not sure of the easiest way to do this correctly, but, you could add in your own post processor that loads up a viscosity field or the two viscosity values and the alpha field. You would then calculate the forces using this local viscosity value.
kmooney is offline   Reply With Quote

Old   August 15, 2012, 09:25
Default
  #3
New Member
 
Claudio
Join Date: May 2010
Location: Boston, MA
Posts: 28
Rep Power: 15
Claudio is on a distinguished road
Thanks Kyle for your reply.

Why then does it work for a turbulent case (BTW, in the transportProperties file I have nu for both phases)?
Does it mean it gives the wrong results for the viscous forces in the turbulent case too?
Even if that is the case I would like to make it work because I am mostly interested in the pressure forces.

In my opinion is doing something different in the force calculation for a laminar case than for a turbulent case. I am not a C++ programmer (always done Fortran), so I am having a bit of a hard time following the logic in forces.C

Any help would be appreciated.

Cheers.
Claudio is offline   Reply With Quote

Old   December 5, 2012, 07:51
Default
  #4
Member
 
Sagun Tripathi
Join Date: Aug 2012
Location: Amherst, USA
Posts: 78
Rep Power: 13
Sagun is on a distinguished road
Hello Kyle and Claudio,

greetings from Germany. I'm getting the same error:

--> FOAM FATAL IO ERROR:
keyword nu is undefined in dictionary "/home/stripathi/OpenFOAM/stripathi-2.1.1/run/tutorials/multiphase/interDyMFoam/ras/floatingBox/constant/transportProperties"

file: /home/stripathi/OpenFOAM/stripathi-2.1.1/run/tutorials/multiphase/interDyMFoam/ras/floatingBox/constant/transportProperties from line 20 to line 32.

From function dictionary::lookupEntry(const word&, bool, bool) const
in file db/dictionary/dictionary.C at line 400.

FOAM exiting


and I'm not even trying to calculate the force on the floating object! I'm attempting to simulate a simple rectangular object floating with 6 DoF in a 2-2 tank with laminar flow.

Could you possibly tell me what am I doing wrong? If necessary, I'll be happy to send you my entire case files.

Thanks,
Sagun
Sagun is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
what the unit of the results got from force function lilinghan8 OpenFOAM 1 June 11, 2012 10:07
Integral Force calculation in CFX 12 - wind blade case LittleBart CFX 0 April 27, 2011 05:04
force function not working in OF 1.6 franzisko OpenFOAM 3 August 4, 2009 15:24
Free surface boudary conditions with SOLA-VOF Fan Main CFD Forum 10 September 9, 2006 13:24
Body force - Does it work? Jan Rusås CFX 5 August 27, 2002 10:50


All times are GMT -4. The time now is 07:43.