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February 1, 2010, 10:17 
Dealing with BC's in OF 1.6

#1 
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Vesselin Krastev
Join Date: Jan 2010
Location: University of Tor Vergata, Rome
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Hello everybody,
I am an almost brand new OF user and I think I have some problems to set appropriate boundary conditons for a 2d incompressible aerodinamic case. The case in question is made up by a rectangular ambient simulating the wind tunnel, with inlet and outlet sections at the two sides. Immersed into the "tunnel" there is a 2d solid profile (initially I started simulating the flow around a very simple geometry, for instance a rectangular section). The inlet value of the velocity field has to be of about 4.28 m/s, and the Reynolds number referred to profile's lenght is of about 10^5. The solver I wish to use is the pisoFoam standard one for incompressible and unsteady flows, initially coupled with a kepsilon standard RAS model. I tried to set the BC's and the other dictionaries (contrloDict, fvSchemes and fvSolution) having a look to the tutorials, but the results I have obtained are not good, because the velocity field seems more like a potential case one rather than a turbulent one, and also because the solution reaches convergence almost instantly. Down below I post the bc's, an image of the velocity field and the other dictionaries contents, so I will be quite happy if someone of us could tell me what I'm doing wrong... Thank you in advance controlDict dictionary: application pisoFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 0.1; deltaT 1e04; writeControl runTime; writeInterval 0.01; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression uncompressed; timeFormat general; timePrecision 6; runTimeModifiable yes; fvSchemes dictionary: ddtSchemes { default Euler; } 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((1A(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 ; } fvSolution dictionary: solvers { p { solver PCG; preconditioner DIC; tolerance 1e06; relTol 0.1; } pFinal { solver PCG; preconditioner DIC; tolerance 1e06; relTol 0; } U { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } UFinal { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } k { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } R { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } nuTilda { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } } PISO { nCorrectors 2; nNonOrthogonalCorrectors 0; } BC's for the velocity field: internalField uniform (0 0 0); boundaryField { INLET { type fixedValue; value uniform (4.28 0 0); } OUTLET { type zeroGradient; } SOLID WALLS { type fixedValue; value uniform (0 0 0); } BC's for the kinematic pressure field: internalField uniform 0; boundaryField { INLET { type zeroGradient; } OUTLET { type fixedValue; value uniform 0; } SOLID WALLS { type zeroGradient; } BC's for the TKE (k): internalField uniform 0.0687; boundaryField { INLET { type fixedValue; value uniform 0.0687; } OUTLET { type zeroGradient; } SOLID WALLS { type kqRWallFunction; Cmu 0.09; kappa 0.41; E 9.8; value uniform 0.0687; } BC's for the TKE dissipation rate (epsilon): internalField uniform 0.109; boundaryField { INLET { type fixedValue; value uniform 0.109; } OUTLET { type zeroGradient; } SOLID WALLS { type epsilonWallFunction; Cmu 0.09; kappa 0.41; E 9.8; value uniform 0.109; } BC's for the Reynolds stresses (R): internalField uniform (0 0 0 0 0 0); boundaryField { INLET { type fixedValue; value uniform (0 0 0 0 0 0); } OUTLET { type zeroGradient; } SOLID WALLS { type kqRWallFunction; } BC's for the turbulent viscosity (nut): internalField uniform 0; boundaryField { INLET { type calculated; value uniform 0; } OUTLET { type calculated; value uniform 0; } SOLID WALLS { type nutWallFunction; Cmu 0.09; kappa 0.41; E 9.8; value uniform 0; } 

February 2, 2010, 07:13 

#2 
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Vesselin Krastev
Join Date: Jan 2010
Location: University of Tor Vergata, Rome
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Any suggestions?


February 2, 2010, 07:32 

#3 
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Jiang
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Location: Japan
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February 2, 2010, 08:52 

#4  
Senior Member
Vesselin Krastev
Join Date: Jan 2010
Location: University of Tor Vergata, Rome
Posts: 364
Rep Power: 11 
Quote:
2I'll try to enlarge epsilon values and then I will post if there are some different results Thanks 

February 2, 2010, 09:07 

#5 
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Vesselin Krastev
Join Date: Jan 2010
Location: University of Tor Vergata, Rome
Posts: 364
Rep Power: 11 
No changes after enlarging epsilon by a 10^2 factor...


September 4, 2012, 11:58 

#6 
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Join Date: Jun 2011
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vkrastev, did you finde how to solve your problem?? I am stucked with the same thing!!
Thank you in advance! 

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