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

lift and drag

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 14, 2009, 09:02
Default lift and drag
  #1
New Member
 
Join Date: Jun 2009
Posts: 9
Rep Power: 16
nicchani is on a distinguished road
Hi, I was searching the forum to find some help to get the lift and drag tool and I finally downloaded the files from the third post in this thread:

http://www.cfd-online.com/Forums/ope...ion-141-a.html

I compiled and now it seems to be ok but I don't know what library i have to call in the controldict file :S

Last edited by nicchani; July 14, 2009 at 11:24.
nicchani is offline   Reply With Quote

Old   July 14, 2009, 11:45
Default
  #2
New Member
 
Join Date: Jun 2009
Posts: 9
Rep Power: 16
nicchani is on a distinguished road
this is what I am using:

functions
(
forces
{
type liftDrag;
functionObjectLibs ("libincompressiblePostProcessing.so");


and when I run it I get this error:

--> FOAM FATAL ERROR : Unknown functiont type liftDrag

Valid functions are :

2
(
turbulentForceAndTorque
laminarForceAndTorque
)


From function functionObject::New(const word& functionType, const Time&, const dictionary&)
in file db/functionObject/functionObject.C at line 89.

FOAM exiting

I don't know why the liftDrag function isn't valid.
nicchani is offline   Reply With Quote

Old   July 14, 2009, 12:10
Default
  #3
Senior Member
 
Steve Hansel
Join Date: Jun 2009
Location: Colorado, USA
Posts: 112
Rep Power: 16
hansel is on a distinguished road
I'm getting force and torque with this, although in the recent 1.5-dev there might be a problem with this library.

functions // this one!
(
forces
{
type forces;
functionObjectLibs ("libforces.so"); //Lib to load
patches (turbine); // change to your patch name
rhoInf 1.225; //Reference density for fluid
CofR (0 0 0); //Origin for moment calculations
}
);
hansel is offline   Reply With Quote

Old   July 14, 2009, 12:26
Default
  #4
New Member
 
Join Date: Jun 2009
Posts: 9
Rep Power: 16
nicchani is on a distinguished road
I am using openfoam 1.4.1 so I don't have that library. If I use turbulentforceandtorque as a force I get some forces on the screen, but what I want is the lift and drag and I have no idea how to get it or if the forces I get on the screen are those. I don't even know what force and torque is. I'm obviously new at this

when I use turbulentforceandtorque I get these forces on screen:

Pressure forces = 1((0 0 0))
Pressure moments = 1((0 0 0))
Viscous forces = 1((0 0 0))
Viscous moments = 1((0 0 0))
Total forces = 1((0 0 0))
Total moments = 1((0 0 0))
nicchani is offline   Reply With Quote

Old   July 15, 2009, 08:01
Default
  #5
New Member
 
Join Date: Jun 2009
Posts: 9
Rep Power: 16
nicchani is on a distinguished road
I have an exe called liftDrag which I guess is the tool for postprocessing. I run the simulation with simplefoam and when it's finished I have run liftDrag but I get all these errors and I don't know what's the problem. Can someone help me with this please? Thanks.

Create mesh for time = 0

Time = 0
Reading U

Reading p

Inlet velocity: (73.45 0 0)
Wall patch 0 named AEROFOIL :
Reference area: 31082.9 Reference length: 500.232 Drag coefficient: 0 Lift coefficient: (0 0 0) Moment coefficient: (0 0 0)
#0 Foam::error:rintStack(Foam::Ostream&) in "/home/nicky/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/nicky/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted: [0xffffe420]
#3 Foam::liftDrag::momentCoefficient(Foam::GeometricF ield<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensioned<double> const&, Foam::word const&, Foam::Vector<double> const&, double const&, double const&) in "/home/nicky/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libincompressiblePostProcessing.so"
#4 main in "/home/nicky/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/liftDrag"
#5 __libc_start_main in "/lib/i686/libc.so.6"
#6 __gxx_personality_v0 in "/home/nicky/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/liftDrag"
Floating point exception
nicchani is offline   Reply With Quote

Old   July 20, 2009, 09:56
Default
  #6
New Member
 
Join Date: Jul 2009
Posts: 14
Rep Power: 16
aaurouss is on a distinguished road
Hi everyone

I tried to use the function described in Hansel's post, but I get an error using it.
Here is what's written in the log file :
************************************************** *****************
attempt to read beyond EOF


file:..............................;/system/controlDict::functions at line 60.


From function ITstream::read(token& t)
in file db/IOstreams/Tstreams/ITread.C at line 64.


FOAM exiting
************************************************** *******************
It seems that there's a library missing or smthg like that

Any idea ?
aaurouss 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
Correct lift but wrong pressure drag - possible? zx Main CFD Forum 4 July 28, 2007 00:38
Lift and Drag Coefficients Reliability Luis FLUENT 2 December 27, 2005 15:45
Drag and Lift Daniel Fisher Phoenics 2 April 8, 2005 04:51
drag and lift coefficient Noé Siemens 5 July 13, 2004 11:21
Fluid mechanics / drag & lift Jamcam Main CFD Forum 0 October 31, 2002 05:39


All times are GMT -4. The time now is 14:48.