[mou_mi]

Hi guys

Would you tell me how I can find Lift and Drag in post-processing step once the simulation is done?

Thank you
mou

Mou,

There's a really good thread over at http://www.cfd-online.com/OpenFOAM_D...tml?1208133899 that should tell you what you need to know, especially if you're using turbFoam.

In my own experience with turbFoam_1, I've noticed that lift and drag coefficients that turbFoam_1 will generate are on a time slice and per-patch basis. I'm not sure how to aggregate those together but it shouldn't be too hard (I hope).

JM

Mou,

There's a really good thread over at http://www.cfd-online.com/OpenFOAM_D...tml?1208133899 that should tell you what you need to know, especially if you're using turbFoam. I've managed to get the custom turbFoam solver working and exporting the right lift/drag entries.

In my own experience with turbFoam_1, I've noticed that lift and drag coefficients that turbFoam_1 will generate are on a time slice and per-patch basis. I'm not sure how to aggregate those together but it shouldn't be too hard (I hope).

If anyone has a process for how to aggregate lift and drag over all the patches in a given model, I'd be very happy to hear about it.

JM

Mou,

There's a really good thread over at http://www.cfd-online.com/OpenFOAM_D...tml?1208133899 that should tell you what you need to know, especially if you're using turbFoam. I've managed to get the custom turbFoam solver working and exporting the right lift/drag entries.

In my own experience with turbFoam_1, I've noticed that lift and drag coefficients that turbFoam_1 will generate are on a time slice and per-patch basis. I'm not sure how to aggregate those together but it shouldn't be too hard (I hope).

If anyone has a process for how to aggregate lift and drag over all the patches in a given model, I'd be very happy to hear about it.

JM

[mou_mi]

Hi Joe

Thank you for your reply. This thread is for finding Lift and Drag during simulation. But I need that after simulation (Post Processing). Is there any code that do that for me?

Mou

[lr103476]

If you have a steady simulation, just run liftDrag. When you have an unsteady simulation, you should include some liftDrag code in your solver such that it writes the forces to files/screen every timestep.

If this answer is still not enough, try to give more details about your problem.

Goodluck, Frank

[mou_mi]

Hi

Thank you for your help, Frank. for adding liftDrag to OF1.4.1, I compiled the /src/postProcessing/incompressible directory and the file libincompressiblePostProcessing.so added to my $FOAM_USER_LIB. but for compiling liftDrag in applications/utilities/postProcessing/wall/liftDrag, after I changed my Make/files to

liftDrag.C

EXE = $(FOAM_USER_APPBIN)/liftDrag

then, wclean&&wmake, I got this error

Making dependency list for source file liftDrag.C
could not open file liftDrag.H for source file liftDrag.C
SOURCE=liftDrag.C ; g++ -m64 -Dlinux64 -DDP -Wall -Wno-strict-aliasing -Wextra -Wno-unused-parameter -Wold-style-cast -march=opteron -O3 -DNoRepository - template-depth-40 -I/usr/local/OpenFOAM/OpenFOAM-1.4.1/src/postProcessing/incompressible/lnInclude -I/usr/local/OpenFOAM/OpenFOAM-1.4.1/src/finiteVolume/lnInclude -I/usr/local/OpenFOAM/OpenFOAM-1.4.1/src/transportModels -I/usr/local/OpenFOAM/OpenFOAM-1.4.1/src/turbulenceModels -I/usr/local/OpenFOAM/OpenFOAM- .4.1/src/LESmodels -I/usr/local/OpenFOAM/OpenFOAM-1.4.1/src/LESmodels/LESdeltas/lnInclude -IlnInclude -I. -I/usr/local/OpenFOAM/OpenFOAM- .4.1/src/OpenFOAM/lnInclude -fPIC -c $SOURCE -o Make/linux64GccDPOpt/liftDrag.o
liftDrag.C:34:22: error: liftDrag.H: No such file or directory
liftDrag.C: In function â:
liftDrag.C:132: error: â has not been declared
liftDrag.C:142: error: â has not been declared
liftDrag.C:152: error: â has not been declared
make: *** [Make/linux64GccDPOpt/liftDrag.o] Error 1

Would anyone tell me what is my problem?

Thank you
mou

[mou_mi]

OK, I found that what was my problem. I needed to change Make/option file also. now it compiled.

mou

[mou_mi]

I face another problem for using liftDrag.
When I implement the liftDrag to solver, that give me Lift and Drag in each timestep during running, it work perfect. But I do not know when I want to use the liftDrag command separately after finishing my run for a time step, it give me error

>>liftDrag . cavity -time 1

/*---------------------------------------------------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.4.1 |
| \ / A nd | Web: http://www.openfoam.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/

Exec : liftDrag . cavity -time 1
Date : Jun 12 2008
Time : 13:01:40
Host : master
PID : 344
Root : /home/mou/OpenFOAM/mou-1.4.1/run/tutorials/turbFoam
Case : cavity
Nprocs : 1
Create time

Create mesh for time = 1

Time = 1
Reading U

Reading p

Inlet velocity: (1 0 0)
#0 Foam::error::printStack(Foam:stream&) in "/usr/local/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/usr/local/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 __restore_rt in "/lib64/tls/libc.so.6"
#3 Foam::liftDrag::momentCoefficient(Foam::GeometricF ield<foam::vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricFie
ld<double,> const&, Foam::dimensioned<double> const&, Foam::word const&, Foam::Vector<double> const&, double
const&, double const&) in "/home/mou/OpenFOAM/mou-1.4.1/lib/linux64GccDPOpt/libliftDrag.so"
#4 main in "/home/mou/OpenFOAM/mou-1.4.1/applications/bin/linux64GccDPOpt/liftDrag"
#5 __libc_start_main in "/lib64/tls/libc.so.6"
#6 __gxx_personality_v0 in "/home/mou/OpenFOAM/mou-1.4.1/applications/bin/linux64GccDPOpt/liftDrag"
Floating exception

do you have any idea about this error?

Thank you
mou

[rieuk]

Hey, same problem as Mohd. I'm looking for something that will give me lift and drag values for my transient simulation results. Anyone got this working yet?

[rieuk]

well got it done using execFlowFunctionObjects. Now to plot the lift and drag values...
These are placed in a separate directory for each timestep...does anyone have a useful script utility that will extract the forces and force coefficients into one file??? Can foamLog do this?? Not that I can see

[Mirage12]

Hello


I would like to refresh this topic and ask the same question :

Would you tell me how I can find Lift and Drag in post-processing step once the simulation is done?


Thanks for your support