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[OpenFOAM-2.1.0] kklOmega RAS Turbulence Model (low Re) |
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January 24, 2012, 09:13 |
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#21 |
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Daniel WEI (老魏)
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Actually, I tried yesterday night for a few times, but got a worse curve.
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January 24, 2012, 19:15 |
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#22 | |
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Sandy Lee
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In addition, do you have literatures about the ERCOFTAC T3A-, T3A, T3B benchmarks and the S&K' s ? Could you sent a copy to me? I have the paper by Walters and Cokljat, however, I could not find the literature of their test cases. Thanks. Sandy sandy.lee37@gmail.com |
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April 11, 2012, 17:24 |
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#23 |
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Luca Bonfiglio
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Hi, I'm trying to use the kklOmega turbolence model to simulate the flow around a 2d naca 0012; here my initial/boundary conditions:
domain: k inletOutlet (5.4e-3) kt inletOutlet (5.4e-3) kl inletOutlet (0) nut inletOutlet (1e-5) nuTilda inletOutlet (1e-5) omega inletOutlet (5.4e5) p outletInlet (0) U inletOutlet (0 2.9886 0.2615) wall: k kqRWallFunction (0) kt inletOutlet (5.4e-3) kl fixedValue (0) nut nutkWallFunction (1e-5) nuTilda zeroGradient omega zeroGradient p zeroGradient U fixedValue (0 0 0) Omega becomes negative after some iterations and the solutions doesn't seem to converge to a reasonable value. I have also problems with the evaluation of the wallShearStress that becomes very high aft of the predicted transitional region. I can't see where I fail. Any suggestion is appreciated. Thank you!! |
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April 11, 2012, 17:39 |
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#24 | |
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Daniel WEI (老魏)
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mesh and then everything works fine. It seems all LRN models have convergence problem.
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April 11, 2012, 18:07 |
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#25 |
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Luca Bonfiglio
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Hi Daniel,
Do you mean that I've to deal with a finer mesh? I'm using simpleFoam so there shouldn't be time step problem, Am I wrong? Thank you for the reply! |
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April 13, 2012, 21:48 |
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#26 |
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Hiya EGP, I have run a kkl-omega case and I am trying to post process the data, however I am having trouble in plotting the Cf versus (Re)x graph to find transition. I have sampled the wall shear stress to find the skin friction coefficient, but I am unsure of getting the (Re)x data from my simulation. Your help would be much appreciated!
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April 23, 2012, 21:53 |
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#27 |
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Tom Li
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Hi everyone
Sorry if this question sounds stupid, but has anyone tried or does anyone know if this model works well with wall functions? (y+ ~ 50) also when I was trying to set up a case, I got this error when trying to run Code:
Starting time loop Time = 4e-06 Courant Number mean: 0.0052655 max: 0.613429 DILUPBiCG: Solving for Ux, Initial residual = 0.999999, Final residual = 2.16698e-08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.38978e-08, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 3.06486e-08, No Iterations 2 DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0996709, No Iterations 238 time step continuity errors : sum local = 2.92672e-07, global = -2.47733e-08, cumulative = -2.47733e-08 DICPCG: Solving for p, Initial residual = 0.853218, Final residual = 9.43328e-07, No Iterations 496 time step continuity errors : sum local = 6.22475e-11, global = -1.59298e-13, cumulative = -2.47734e-08 DILUPBiCG: Solving for kt, Initial residual = 1, Final residual = 6.62784e-06, No Iterations 1 DILUPBiCG: Solving for kl, Initial residual = 1, Final residual = 1.11568e-07, No Iterations 2 bounding kl, min: 0 max: 0.029737 average: 0.0050596 --> FOAM FATAL ERROR: request for volScalarField k from objectRegistry region0 failed available objects of type volScalarField are 30 ( ((((1-exp((-sqrt((((sqr((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)|nu)|(omega+omegaMin)))|Av)))*CmuStd)*sqrt(((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)))*min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))) (kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)) kt_0 nut (((CR*(1-exp((-max((((kt|nu)|((1.41421*mag(skew(grad(U))))+ROTVSMALL))-CbpCrit),0)|Abp))))*omega)|((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL))+SMALL)) kt kt_0_0 ((CrNat*(1-exp((-max((((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu)-(CnatCrit|((1-exp((((-Cnc*sqrt(kl))*y)|nu)))+ROTVSMALL))),0)|Anat))))*(1.41421*mag(skew(grad(U))))) (min((((((((C11*(1-exp(((-CtauL*(kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)))|sqr(((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))*omega)+ROOTVSMALL))))))*(1.41421*mag(skew(grad(U)))))*sqr(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))))*sqrt((kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt))))*min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin))))|nu)+((((C12*(1-exp((-sqr(max((((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu)-CtsCrit),0))|Ats))))*((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu))*sqr(y))*(1.41421*mag(skew(grad(U)))))),((0.5*(kl+(kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt))))|sqrt((2*magSqr(symm(grad(U)))))))*(2*magSqr(symm(grad(U))))) (kt+kl) kl_0_0 kl_0 (sqrt((kt+kl))|(omega+omegaMin)) (nu*magSqr(grad(sqrt(kt)))) (min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)) (1-exp((((-Cnc*sqrt(kl))*y)|nu))) (nu*magSqr(grad(sqrt(kl)))) nu ((((((1-exp((-sqrt((((sqr((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)|nu)|(omega+omegaMin)))|Av)))*min((kl|(Cint*((kl+kt)+kMin))),1.0))*(1|(A0+(As*(sqrt((2*magSqr(symm(grad(U)))))|(omega+omegaMin))))))*sqrt(((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)))*min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin))))*(2*magSqr(symm(grad(U))))) (2*magSqr(symm(grad(U)))) min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin))) kl (((((1-exp((-sqrt((((sqr((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)|nu)|(omega+omegaMin)))|Av)))*min((kl|(Cint*((kl+kt)+kMin))),1.0))*(1|(A0+(As*(sqrt((2*magSqr(symm(grad(U)))))|(omega+omegaMin))))))*sqrt(((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)))*min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))) p min((((((((C11*(1-exp(((-CtauL*(kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt)))|sqr(((min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))*omega)+ROOTVSMALL))))))*(1.41421*mag(skew(grad(U)))))*sqr(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))))*sqrt((kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt))))*min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin))))|nu)+((((C12*(1-exp((-sqr(max((((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu)-CtsCrit),0))|Ats))))*((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu))*sqr(y))*(1.41421*mag(skew(grad(U)))))),((0.5*(kl+(kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt))))|sqrt((2*magSqr(symm(grad(U))))))) ((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+kMin))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)))*kt) (1.41421*mag(skew(grad(U)))) omega ((sqr(y)*(1.41421*mag(skew(grad(U)))))|nu) y ) From function objectRegistry::lookupObject<Type>(const word&) const in file /opt/OpenFOAM/OpenFOAM-2.1.x/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 131. FOAM aborting #0 Foam::error::printStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::error::abort() in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const& Foam::objectRegistry::lookupObject<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >(Foam::word const&) const in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #3 Foam::incompressible::turbulentMixingLengthDissipationRateInletFvPatchScalarField::updateCoeffs() in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #4 Foam::incompressible::RASModels::kkLOmega::correct() in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #5 in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/bin/pisoFoam" #6 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #7 in "/opt/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/bin/pisoFoam" Aborted Thanks Last edited by strikeraj; April 23, 2012 at 22:53. |
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April 25, 2012, 09:49 |
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#28 |
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strikeraj,
You need to have a y+ of less then one cuz this model uses near wall approach and you can't use a wall function, it simply does not give you transition. |
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April 25, 2012, 21:20 |
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#29 | |
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Sandy Lee
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Yes Strikeraj, I agree to Vahini. I guess, this method should be given the same fine grids as like as LES if you solve a three-dimension problem ... |
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April 25, 2012, 21:21 |
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#30 |
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Tom Li
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Thanks Sandy and Vahini
I guess I missed the obvious part in the model lol |
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April 27, 2012, 08:52 |
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#31 |
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Hey!
How does one know, that the kinamatic turbulent viscosity nut and nuTilda have to be set to the viscosity of the fluid (1.5e-5)? And why did you calculate omega with the formula: nut = kt/omega In the official paper from D. Keith Walters it says that: mut = rho * Cmu,std * kt/omega with Cmu,std = 0.09 so in your formula Cmu,std is missing. greetings Christian |
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May 6, 2012, 16:01 |
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#32 |
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Titus van den Brink
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I would like to use the new kklomega model for a Velomobile study (A typical low Reynolds case). Would anyone of you be willing to give me some advice? See http://openfoamforvelomobiling.blogspot.com/. The Velox team (http://www.hptdelft.nl/en/) have done windtunnel tests on their body. It would be very interesting to compare their results with those of the kklomega model...
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May 6, 2012, 20:29 |
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#33 |
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Sandy Lee
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what is the "new kklomega model " ?
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May 7, 2012, 03:19 |
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#34 |
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Titus van den Brink
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Dear Sandy
I mean this: Version 2.1.0 includes the k-kl-omega (low-Re) model for Reynolds-average simulation of incompressible flows with a boundary layer that undergoes a transition from laminar to turbulent flow. The model is described in D. K. Walters and D. Cokljat, J. Fluids Eng. 130:121401 (2008) and is based on the model k-w with an additional transport equation included to predict low-frequency velocity fluctuations that trigger transition in the boundary layer. |
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June 21, 2012, 10:05 |
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#35 |
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Mads Reck
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Hey,
I have a 2D airfoil simulation with settings like the above. Mesh is from blockMesh, checkMesh is fine, standard kOmegaSST converges but applying kkLOmega crashes. omega explodes, I tried all kinds of limiters but they have no effect. Any idea? Help would be greatly appreciated Mads
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June 21, 2012, 10:21 |
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#36 | |
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Daniel WEI (老魏)
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June 21, 2012, 22:32 |
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#38 |
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Joe
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I have tried running this without wall functions, but openfoam will replace the files in the 0 folder with files that have wall functions and back up the old ones having a .old extension. How can I run a turbulence model (kklomega inthis case) without wall functions?
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June 22, 2012, 02:01 |
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#39 |
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RDG
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I think you need to edit the 0/nut file that openfoam creates and remove the wall function for nut.
Then you can move back your .old files to the original. |
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June 22, 2012, 12:20 |
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#40 |
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Joe
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