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MRFSimpleFoam + AMI in 2.1.0 vs GGI in 1.5-dev |
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#1 |
New Member
Marcel Günter
Join Date: Mar 2012
Location: Stuttgart, Germany
Posts: 20
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hello everyone,
I recently managed to run the ERCOFTAC Centrifugal Pump validation test case in a recent version of OpenFoam 1.5-dev with the help of this forum (thanks again!) now I want to run this exact same case in OpenFoam 2.1.0 with AMI interfaces instead of GGI. the turbulence model (k-epsilon) and all the boundary conditions are exactly the same as in the 1.5-dev case except for the pressure-outlet. in 1.5-dev the pressure outlet is set as "fixedmeanvalue", unfortunately this bc doesn't exist any more in 2.1.0, so i defined it as "fixedvalue". the case converges, though not as good as in 1.5-dev. the results for U make sense but still differ from those i got in 1.5-dev. what puzzles me the most are the results for p. the pressure gradient is just inverted! see for yourselves, i uploaded the pictures. does anyone have an idea how this could happen or what i could do to get better results? best regards, Marcel |
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#2 |
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Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
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Hi,
Are the two cases rotating in the same direction? Best Regards, Paulo Rocha |
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#3 |
New Member
Marcel Günter
Join Date: Mar 2012
Location: Stuttgart, Germany
Posts: 20
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yes, they are. i just checked it again, to be safe.
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#4 |
Senior Member
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
Posts: 238
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could you please post your initial U and p / p_rgh file and fvSolution, fvSchemes? I probably can't help put I'd like to take a look.
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#5 |
Senior Member
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
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...because I think your geometry is qite challanging for your turbulence model. Did you try with LES in combination with DMM subgrid scale model developed by the LTT Rostock and a SimpleGridFilter to allow backscatter? This would account better for the Influence of your geometry on the turbulence.
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#6 |
Member
wided
Join Date: Jul 2010
Posts: 54
Rep Power: 16 ![]() |
Hi marcelgt87,
I also wanted to do the same comparison you did using the ERCOFTAC validation case. This is because I also did not obtain the same P for a very simple case that I tried to compare using both approaches which you used ... It would be nice if you give some details about your schemes and solutions dictionaries. Regards |
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#7 |
New Member
Marcel Günter
Join Date: Mar 2012
Location: Stuttgart, Germany
Posts: 20
Rep Power: 14 ![]() |
sorry, that it took so long. here are my files for OF 2.1.0.
U: Code:
internalField uniform (0 0 0); boundaryField { INLET { type surfaceNormalFixedValue; refValue uniform -11.4; } OUTLET { type zeroGradient; } BLADE_ROT { type fixedValue; value uniform (0 0 0); } BLADE_STAT { type fixedValue; value uniform (0 0 0); } HUB_SHROUD { type empty; } AMI_INT { type cyclicAMI; value $internalField; } AMI_EXT { type cyclicAMI; value $internalField; } } Code:
internalField uniform 0; boundaryField { INLET { type zeroGradient; } OUTLET { type fixedValue; value uniform 0; } BLADE_ROT { type zeroGradient; } BLADE_STAT { type zeroGradient; } HUB_SHROUD { type empty; } AMI_INT { type cyclicAMI; value $internalField; } AMI_EXT { type cyclicAMI; value $internalField; } } Code:
solvers { p { solver GAMG; smoother GaussSeidel; cacheAgglomeration true; nCellsInCoarsestLevel 20; agglomerator faceAreaPair; mergeLevels 1; tolerance 1e-08; relTol 0.05; } pFinal { solver GAMG; smoother GaussSeidel; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; tolerance 1e-06; relTol 0; } "(U|k|epsilon)" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-07; relTol 0.1; } "(U|k|epsilon)Final" { solver PBiCG; preconditioner DILU; tolerance 1e-05; relTol 0; } } PIMPLE { nOuterCorrectors 4; nCorrectors 1; nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; } SIMPLE { nNonOrthogonalCorrectors 0; } relaxationFactors { fields { p 0.3; } equations { U 0.7; k 0.9; "epsilon.*" 0.9; } } cache { grad(U); } Code:
ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) Gauss limitedLinearV 1; div(phi,k) Gauss limitedLinear 1; div(phi,epsilon) Gauss limitedLinear 1; div(phi,R) Gauss limitedLinear 1; div(R) Gauss linear; div(phi,nuTilda) Gauss limitedLinear 1; div((nuEff*dev(T(grad(U))))) 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 ; } @wiedangel: did you succeed? did you get any results with that comparison? could you give me some more details about what exactly you did? thank you! marcel |
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#8 |
Senior Member
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
Posts: 238
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Hi Marcel, I would use OUTLET { type zeroGradient; } for p since I had some funny coordinate-dependent effects using fixedValue 0 at my outlets.
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#9 |
New Member
Marcel Günter
Join Date: Mar 2012
Location: Stuttgart, Germany
Posts: 20
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i just tried to do what you said. i set the outlet to zerogradient. as a result openfoam tells me to provide a reference value for p. when i do that (refvalue 0 and refcell 0) the calculation doesn't converge and eventually crashes. i also tried setting the outlet as zerogradient and the inlet as fixedvalue 0, with the same result.
is there anything i overlooked? regards, marcel |
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#10 |
Senior Member
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
Posts: 238
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what does it look like when you use a high refvalue?
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#11 |
New Member
Marcel Günter
Join Date: Mar 2012
Location: Stuttgart, Germany
Posts: 20
Rep Power: 14 ![]() |
quite the same
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#12 |
Member
Ye Zhang
Join Date: Dec 2009
Location: Delft,Netherland
Posts: 92
Rep Power: 16 ![]() |
Hi Marcel,
Could you please send me a copy of testcase of ERCOFTAC Centrifugal Pump? I did not download it successfully. Thank you so much! My email address: dlutyezhang@gmail.com or you can use this mail to share it by Dropbox. Again thanks Best regards, Ye |
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#13 |
Member
Lisandro Maders
Join Date: Feb 2013
Posts: 98
Rep Power: 13 ![]() |
Hey guys, did you sort the pressure problem? If so, what was the problem and how do you manage to fix that?
Appreciate a lot your answer! Lisandro |
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Tags |
ami, ggi, kepsilon, mrfsimplefoam |
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