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Old   February 16, 2009, 10:57
Default Hi FOAMers! In order to fin
  #41
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Hi FOAMers!

In order to find a proper case set up, I am considering a wing with an AoA = 8, that it is easier to simulate and has not problem with flow detachment. After trying different schemes combinations, I applied:
- gradSchemes: faceMDLimited Gauss linear 0.5
- divSchemes: Gauss upwind
everywhere, except for div(phi,U) Gauss limitedLinearV 1
- laplacianSchemes: Gauss linear corrected.


A comparison between OF and Fluent is presented in the following pictures:


As you can see, two problems are still opened:

1)There is a big gap between OF and Fluent converged cd value: the latter is higher of about 50% in respect to OF. Comparing pressure contours, I have the same general behaviour, but different max and min values. Might it be connected with wallFunctions? I have patch 0 named surf y+: min: 1.27842 max: 52.8088 average: 10.0848 in OF and Yplus max 168.2676 in Fluent... Remember that I am using realizableKE on both.

2)OF cl and cd shows wiggles in their histories, while Fluent values becomes smooth after about 300 iterations. It seems like OF values stop converging after a while. I tried to decrease tolerances for U and p, but no improvement was obtained. Is this problem connected with numerical schemes, relaxation factors and so on or is this more a wrong physical condition?

Suggestions are welcome!!

Maddalena.
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Old   February 16, 2009, 16:09
Default Hi, I have similar problem
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Mathias Kvick
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Hi,

I have similar problems, here are plots of the pressure coefficient at a cross section of the upper and lower surface of my wing.





As you can see, the results does not look good at the upper surface, on the lower surface it looks better, but still not good.

As I understood it Fluent uses the same wallfunctions as I have in my case..

Let me know if you find out something..
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Old   February 16, 2009, 16:34
Default In Genral different solvers gi
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In Genral different solvers give different results. However, 50% difference on drag seems massively to big for me. However I currently have no real explanation for it. It might be possible that the turbulence models behave different in the transition area. I get very simular results on meshes with prism layers (= fewer transition). I never tried it without.

Regards BastiL
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Old   February 18, 2009, 13:33
Default Hi FOAMers, In order to under
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Hi FOAMers,
In order to understand why OF and Fluent converge to such different coefficient values, I analyzed the single forces contribution. Here the results:

<u>Fluent</u>
pressure force: (-0,4409 0,7928 10,5498)
viscous force: (0,4121 -0,0003 0,0159)
cl: 0,63170 (converged)
cd: 0,08700 (converged)
yPlus : min 14,79 max 129,71

<u>OF</u>
pressure force: (-0,7441 0,720801 10,7649)
viscous force: (0,07900 -0,0011 0,0045)
cl: 0,6538 (not converged)
cd: 0,0504 (not converged)
yPlus: min 1,28 max 52,81

In particular, the contribution along x axis is the main cause of such a difference in the resulting aerodynamic coefficients, and since I have an AoA = 8, this is more pronounced in cd. In addition, besides I am using the same Hi-Re turbulence model in the two solvers (realizableKE), the same standard wall function including wall roughness and the same mesh, the yPlus values are different. Note that Fluent values are close to experimental ones.

In order to have an insight on this points, I run a inviscid case (viscosity &rarr; inviscid in Fluent and slip bc at wall in OF) with a A0A = 0. Here the results:

<u>Fluent</u>
pressure force: (0,3334 -0,4700 0,5896)
viscous force: (0 0 0) (Ok!)
cl: 0.035580496
cd: 0.020121824

<u>OF</u>
pressure force: (0,1937 -0,5229 0,5089)
viscous force: (3,011e-5 -8,3081e-6 -2,4340e-5) (ok!)
cl: 0,0307
cd: 0,01169

As you can see, x-component of pressure force is very different in the two solvers, it is the main reason of the 50% difference in cd here, and so it is to the viscous original case.

I have been searching in the message board and surfing the web for quite a while now, in order to find an explanation, but with no luck. I have still some open questions:

1)Why there is such a difference between the two solvers in pressure calculation? As reported by Mathias above, the pressure distribution in chord-wise direction is different as well.
2)Why there is such a difference in y+, besides the same mesh, the same wall function and the same grid?
3)Is there something that I am missing (The entire case set up is explained in detail in the previous posts)?
4)Is there any hidden tricks in Fluent that let Fluent simulation converge? Schemes? Boundary conditions?
5)Besides using a prism-layer mesh, is there any other suggestions? Note that I do not use a prism-layer mesh since:
- It is difficult to obtain a good mesh with my model
- I do not want to end up with millions of cells to have a first estimation of values,
- Doing a geometry sensitivities study with a prism-layer mesh will take me more time in creating mesh than running the case itself.

Any help will be appreciated!!!
Regards,

Maddalena
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Old   February 19, 2009, 04:38
Default Hello Maddalena,
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Hello Maddalena,
Good work in regards with inviscid computation for comparing pressure forces.

1. I realized you are using Gaussian Node based gradients in Fluent which is recommended for unstructured mesh. In Openfoam are you using something similar type ? Still i am a new to OpenFoam , may be how much this may influence i dont know.

2. To be sure you have to set the kinematic viscosity [m^2/s] in OpenFoam, which is Default.i did this mistake once so just reminding you.

3.The physical distance from the wall to the next cell grid may be different if it is cell centred schemes or its counter part. Make sure that its taking the same physical distance for Y+...

4. There are lots of variables and modeling assumptions involved here, quite difficult to find the exact one for turbulent flows. But looking at your results for potential flow, its seems there may be some better Numerical settings can be used for OpenFoam.

Have Fun. Your contribution will end up in some better understanding of OpenFoam.
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Old   February 24, 2009, 08:14
Default Hi Maddalena, Any success
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Mathias Kvick
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Hi Maddalena,

Any success in reducing the difference between the two calculations?

//Mathias
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Old   February 24, 2009, 11:52
Default Hi Mathias, in the last days
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Hi Mathias,
in the last days I have been busy with other stuff and I haven't tested anything new. I will try some more settings, included what Maruthamuthu suggested, as soon as I will have some free time. In the meanwhile, please let me know of every updates/news/improvement you have!
Cheers,
Maddalena
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Old   February 27, 2009, 07:39
Default Hi Maddalena, from your pro
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Hi Maddalena,

from your profile I have noticed that you are working in Trieste.

I am also from Trieste.

Recently I have compared CFX-11 and OF-1.5 for prediction of the flow around NACA0012.

If you are interested to contact me, (to arrange a meeting in TS) you can find my e-mail address in the profile.

Have a nice day

Mitja
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Old   March 2, 2009, 04:14
Default hi Maruthamuthu Venkatraman
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hi Maruthamuthu Venkatraman

i am from india,In order to find a proper convergent solution, I am considering a naca 0012 airfoil case with an AoA = 4, can u please send me how wil u know that whether the solution is converged or not like fluent v wil get at some point v wil get that the solution is converged,but i dont know how v wil get in openfoam 1.4.1.....
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Old   March 2, 2009, 04:14
Default hi Maruthamuthu Venkatraman si
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hi Maruthamuthu Venkatraman sir

i am from india,In order to find a proper convergent solution, I am considering a naca 0012 airfoil case with an AoA = 4, can u please send me how wil u know that whether the solution is converged or not like fluent v wil get at some point v wil get that the solution is converged,but i dont know how v wil get in openfoam 1.4.1.....
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Old   March 2, 2009, 04:29
Default Hello Naveen,
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Hello Naveen,
Iam glad to see your progress in using OpenFoam.For your calculation i would recommend you to check the convergence of the drag and lift coeffcient.

You need not to address people here in the forum with Sir. Just put your question clearly and if people dont have time to reply you then better try it out...

I would recommend you to read Fluid mechanics book by Munsion, Youung and Okashi under the Section "Flow over the immersed bodies". Also Fluid Mechanics by Frank M white.

Most of the external aerodynamic theories and expoerimental results are there. You shall make some test case and check your answers...

Good luck
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Old   March 2, 2009, 23:12
Default Hi Fomers, i am also facin
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Vishal Jambhekar
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Hi Fomers,

i am also facing some issues using sonicTurboFoam for Supersonic Flow. i am mainly interested to capture shock boundary layer interaction.

Please have a look at this post.


Use this link to go directly to the discussion:
http://www.cfd-online.com/cgi-bin/Op...ow.cgi?1/11454
__________________
Cheers,

Vishal Jambhekar...
"Simulate the way ahead......!!!"
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Old   March 3, 2009, 08:34
Default Hi Foamers, when I tried to
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Wolfgang Heydlauff
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Hi Foamers,

when I tried to simulate an airfoil I realized that to further the boundary borders were, the better the solution got (compared to some windtunnel results). best results I got with a distance of the boundary borders of approx. 160 time the chordlenght (!!). (komegaSST-Model).

Since OF has no farfield-correction like "Fluent" or "Flower" I think this is at least necessary.

Improving the results a lot I also change the top and bottom boundary type from symmetryPlane to inlet. If far away you get better undisturbed stream flow at the airfoil itself. If symmetryPlane is used, the airflow is changing angle to apply the symmetryPlane conditions. In bad case, the AoA decreases.
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Old   April 15, 2009, 04:40
Default Conclusion
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Hello FOAMers,
in order to obtain better convergence and results closer to Fluent for my external aerodynamic simulation, I changed one more time my fvSchemes, following some suggestions I had from HRV. Now it looks like this:
  • gradSchemes: faceMDLimited Gauss linear 0.5;
  • divSchemes: Gauss GammaV 1 on div(phi,U); Gauss upwind everywhere else.
  • laplacianSchemes: Gauss linear limited 0.33 on laplacian(DepsilonEff,epsilon), Gauss linear limited 0.5 everywhere else.
  • interpolationSchemes: linear;
  • snGradSchemes: limited 0.5;
Moreover, I increased tolerance and relTol for every variable:
{
...
tolerance 1e-09;
relTol 0.01;
}
This helped me to obtain better numerical convergence. However, a certain difference between OF and Fluent still remain (alpha = 8):
  • Fluent:
    • CL: 0.6317
    • CD: 0.0870
    • pmax:137
    • pmin:-199
  • OF:
    • CL: 0.6596
    • CD: 0.0522
    • pmax: 115
    • pmin: -179
I could not find a numerical set-up or domain discretisation that allows me to obtain a smaller gap between the two solvers, so I can say that this is the best I could have with the standard OF distribution for a case similar to mine.
Since Fluent results are closer to experimental values, I can conclude that OF 1.5 underestimates aerodynamic coefficients as a consequence of a numerically different pressure field around the wing.
Please, feel free to add anything in addition to this.
Regards,
Maddalena
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Old   April 15, 2009, 11:32
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HI Maddalena!
HI Foamers!

Just by a fluke I found this thread. I am also simulating a flow around an airfoil and I am enthused of the possibility of writing cl cd to file. But I am struggling with some difficulties. Is there anywhere more information about this function??

Best Regards
Camoesas

Last edited by camoesas; April 16, 2009 at 03:12.
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Old   April 20, 2009, 08:20
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HI Everybody!

I still have not found more information about the forceCoeffs function. Altough it is working fine. But in the end I get this error message:

*** glibc detected *** simpleFoam: corrupted double-linked list: 0x0000000000cc1ae0 ***
Inconsistency detected by ld.so: dl-open.c: 260: dl_open_worker: Assertion `_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT' failed!


Do I have to worry? I have already searched this board but without results.

Any ideas? Anyone gets this message too?

Best Regards
Camoesas
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Old   May 22, 2009, 05:00
Default Cl value not macths with experimental value
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VENKATESH T LAMANI
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Hi,
This venkatesh solved the Airfoil case NACA 0012.
Problem Description:NACA 0012 airfoil with Reynolds number=3e6,Mach number=0.85,2D case and AOA 1.Experimental value of Cl is 0.30 ,but it showing 0.06125 .this is my U ,P and control Dictionary.


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


dimensions [0 2 -2 0 0 0 0];

internalField uniform 101325;

boundaryField
{
farfield
{
type zeroGradient;

}

airfoil
{
type zeroGradient;
}

frontAndBackPlanes
{
type empty;
}
}


// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


dimensions [0 1 -1 0 0 0 0];

internalField uniform (289.12 5.04 0);

boundaryField
{
farfield
{
type inletOutlet;
inletValue uniform (289.12 5.04 0);
value uniform (289.12 5.04 0);
}

airfoil
{
type fixedValue;
value uniform (0 0 0);
}

frontAndBackPlanes
{
type empty;
}
}


// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object controlDict;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application simpleFoam;

startFrom startTime;

startTime 0;

stopAt endTime;

endTime 1000;

deltaT 1;

writeControl timeStep;

writeInterval 250;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression uncompressed;

timeFormat general;

timePrecision 6;

graphFormat raw;

runTimeModifiable yes;

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

forceCoeffs
{
type forceCoeffs;
functionObjectLibs ("libforces.so");
patches (airfoil); //change to your patch name
rhoInf 1.225;
CofR (0 0 0);
liftDir (0.0174 0.9998 0);
dragDir (0.9998 0.0174 0);
pitchAxis (0 0 0);
magUInf 289.16;
lRef 1;
Aref 1;
}
);


// ************************************************** *********************** //
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;

class dictionary;
object fvSchemes;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss upwind;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phi,nuTilda) Gauss upwind;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}

laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(U) linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p;
}


// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p PCG
{
tolerance 1e-06;
relTol 0;
preconditioner DIC;
};
U PBiCG
{
tolerance 1e-06;
relTol 0;
preconditioner DILU;
};
k PBiCG
{
tolerance 1e-06;
relTol 0;
preconditioner DILU;
};
epsilon PBiCG
{
tolerance 1e-06;
relTol 0;
preconditioner DILU;
};
R PBiCG
{
tolerance 1e-06;
relTol 0;
preconditioner DILU;
};
nuTilda PBiCG
{
tolerance 1e-06;
relTol 0;
preconditioner DILU;
};
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}

relaxationFactors
{
p 0.3;
U 0.7;
k 0.7;
epsilon 0.7;
R 0.7;
nuTilda 0.7;
}
PISO
{
momentumPredictor yes;
nCorrectors 2;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}


// ************************************************** *********************** //
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;

class dictionary;
object transportProperties;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

transportModel Newtonian;

nu nu [0 2 -1 0 0 0 0] 9.63e-05;

CrossPowerLawCoeffs
{
nu0 nu0 [0 2 -1 0 0 0 0] 0;
nuInf nuInf [0 2 -1 0 0 0 0] 0;
m <> [0 0 0 0 0 0 0] 0;
n <> [0 0 0 0 0 0 0] 0;
}

BirdCarreauCoeffs
{
nu0 nu0 [0 2 -1 0 0 0 0] 0;
nuInf nuInf [0 2 -1 0 0 0 0] 0;
k <> [0 0 0 0 0 0 0] 0;
n <> [0 0 0 0 0 0 0] 0;
}


// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object RASProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

RASModel laminar;

turbulence off;

printCoeffs on;

laminarCoeffs
{
}

kEpsilonCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphaEps 0.76923;
}

RNGkEpsilonCoeffs
{
Cmu 0.0845;
C1 1.42;
C2 1.68;
alphak 1.39;
alphaEps 1.39;
eta0 4.38;
beta 0.012;
}

realizableKECoeffs
{
Cmu 0.09;
A0 4.0;
C2 1.9;
alphak 1;
alphaEps 0.833333;
}

kOmegaSSTCoeffs
{
alphaK1 0.85034;
alphaK2 1.0;
alphaOmega1 0.5;
alphaOmega2 0.85616;
gamma1 0.5532;
gamma2 0.4403;
beta1 0.0750;
beta2 0.0828;
betaStar 0.09;
a1 0.31;
c1 10;

Cmu 0.09;
}

NonlinearKEShihCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphak 1;
alphaEps 0.76932;
A1 1.25;
A2 1000;
Ctau1 -4;
Ctau2 13;
Ctau3 -2;
alphaKsi 0.9;
}

LienCubicKECoeffs
{
C1 1.44;
C2 1.92;
alphak 1;
alphaEps 0.76923;
A1 1.25;
A2 1000;
Ctau1 -4;
Ctau2 13;
Ctau3 -2;
alphaKsi 0.9;
}

QZetaCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphaZeta 0.76923;
anisotropic no;
}

LaunderSharmaKECoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphaEps 0.76923;
}

LamBremhorstKECoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphaEps 0.76923;
}

LienCubicKELowReCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphak 1;
alphaEps 0.76923;
A1 1.25;
A2 1000;
Ctau1 -4;
Ctau2 13;
Ctau3 -2;
alphaKsi 0.9;
Am 0.016;
Aepsilon 0.263;
Amu 0.00222;
}

LienLeschzinerLowReCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphak 1;
alphaEps 0.76923;
Am 0.016;
Aepsilon 0.263;
Amu 0.00222;
}

LRRCoeffs
{
Cmu 0.09;
Clrr1 1.8;
Clrr2 0.6;
C1 1.44;
C2 1.92;
Cs 0.25;
Ceps 0.15;
alphaEps 0.76923;
}

LaunderGibsonRSTMCoeffs
{
Cmu 0.09;
Clg1 1.8;
Clg2 0.6;
C1 1.44;
C2 1.92;
C1Ref 0.5;
C2Ref 0.3;
Cs 0.25;
Ceps 0.15;
alphaEps 0.76923;
alphaR 1.22;
}

SpalartAllmarasCoeffs
{
alphaNut 1.5;
Cb1 0.1355;
Cb2 0.622;
Cw2 0.3;
Cw3 2;
Cv1 7.1;
Cv2 5.0;
}

wallFunctionCoeffs
{
kappa 0.4187;
E 9;
}

// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class polyBoundaryMesh;
location "constant/polyMesh";
object boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

3
(
farfield
{
type patch;
nFaces 292;
startFace 13738;
}
airfoil
{
type wall;
nFaces 152;
startFace 14030;
}
frontAndBackPlanes
{
type empty;
nFaces 13960;
startFace 14182;
}
)

// ************************************************** *********************** //
Can you tell me where i am wrong .
waiting for replay
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Old   June 10, 2009, 02:55
Default solving multielement airfoil case in openfoam
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NAVEEN.K.M
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does any one know how to solve multielement airfoil case in openfoam which is imported from gambit...and suggest me how to set boundary conditions for mach no 0.15..
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Old   June 11, 2009, 02:03
Default Multielement airfoil analysis
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NAVEEN.K.M
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HI EVERYBODY

Does any one know how to solve mutielement airfoil in openfoam 1.4.1 or 1.5...if any one knows suggest me how to set boundary conditions which is imported from gambit..
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Old   June 11, 2009, 02:18
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NAVEEN.K.M
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hi maruthamuthu_venkatraman

my self NAVEEN from INDIA...i hav completed my naca 0012 airfoil analysis case in openfoa 1.4.1 and 1.5....i got good results in both the versions...thanks for your suggestions....now i am doing MTech project on multielement airfoil analysis with double slotted flaps and i hav completed my grid in gambit(c-grid) and now i need to solve in openfoam...i am getting some errors like this during solving in openfoam 1.4.1

#0 Foam::error:rintStack(Foam::Ostream&) in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 Foam::fvMatrix<double>::solve(Foam::Istream&) in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#5 main in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linux64GccDPOpt/simpleFoam"
#6 __libc_start_main in "/lib64/libc.so.6"
#7 Foam::regIOobject::readIfModified() in "/home/openfoam14/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linux64GccDPOpt/simpleFoam"

can u give me some suggestions whare i am going wrong and also suggest how to set boundary conditions.....
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