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January 24, 2012, 10:13 

#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, 20:15 

#22  
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Sandy Lee
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Quote:
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 

April 11, 2012, 17:24 

#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 (5.4e3) kt inletOutlet (5.4e3) kl inletOutlet (0) nut inletOutlet (1e5) nuTilda inletOutlet (1e5) omega inletOutlet (5.4e5) p outletInlet (0) U inletOutlet (0 2.9886 0.2615) wall: k kqRWallFunction (0) kt inletOutlet (5.4e3) kl fixedValue (0) nut nutkWallFunction (1e5) 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!! 

April 11, 2012, 17:39 

#24  
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Daniel WEI (老魏)
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Quote:
mesh and then everything works fine. It seems all LRN models have convergence problem.
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~ Daniel WEI  NatHaz Modeling Laboratory Department of Civil & Environmental Engineering & Earth Sciences University of Notre Dame, USA Email  My Personal CFD Blog 

April 11, 2012, 18:07 

#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! 

April 13, 2012, 21:48 

#26 
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Hiya EGP, I have run a kklomega 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!


April 23, 2012, 21:53 

#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 = 4e06 Courant Number mean: 0.0052655 max: 0.613429 DILUPBiCG: Solving for Ux, Initial residual = 0.999999, Final residual = 2.16698e08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.38978e08, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 3.06486e08, No Iterations 2 DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0996709, No Iterations 238 time step continuity errors : sum local = 2.92672e07, global = 2.47733e08, cumulative = 2.47733e08 DICPCG: Solving for p, Initial residual = 0.853218, Final residual = 9.43328e07, No Iterations 496 time step continuity errors : sum local = 6.22475e11, global = 1.59298e13, cumulative = 2.47734e08 DILUPBiCG: Solving for kt, Initial residual = 1, Final residual = 6.62784e06, No Iterations 1 DILUPBiCG: Solving for kl, Initial residual = 1, Final residual = 1.11568e07, 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 ( ((((1exp((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*(1exp((max((((ktnu)((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*(1exp((max((((sqr(y)*(1.41421*mag(skew(grad(U)))))nu)(CnatCrit((1exp((((Cnc*sqrt(kl))*y)nu)))+ROTVSMALL))),0)Anat))))*(1.41421*mag(skew(grad(U))))) (min((((((((C11*(1exp(((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*(1exp((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)) (1exp((((Cnc*sqrt(kl))*y)nu))) (nu*magSqr(grad(sqrt(kl)))) nu ((((((1exp((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 (((((1exp((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*(1exp(((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*(1exp((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/OpenFOAM2.1.x/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 131. FOAM aborting #0 Foam::error::printStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::error::abort() in "/opt/OpenFOAM/OpenFOAM2.1.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/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #3 Foam::incompressible::turbulentMixingLengthDissipationRateInletFvPatchScalarField::updateCoeffs() in "/opt/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #4 Foam::incompressible::RASModels::kkLOmega::correct() in "/opt/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #5 in "/opt/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/bin/pisoFoam" #6 __libc_start_main in "/lib/x86_64linuxgnu/libc.so.6" #7 in "/opt/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/bin/pisoFoam" Aborted Thanks Last edited by strikeraj; April 23, 2012 at 22:53. 

April 25, 2012, 09:49 

#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. 

April 25, 2012, 21:20 

#29  
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Sandy Lee
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Quote:
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 threedimension problem ... 

April 25, 2012, 21:21 

#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 

April 27, 2012, 08:52 

#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 (1.5e5)? 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 

May 6, 2012, 16:01 

#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...


May 6, 2012, 20:29 

#33 
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Sandy Lee
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what is the "new kklomega model " ?


May 7, 2012, 03:19 

#34 
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Titus van den Brink
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Dear Sandy
I mean this: Version 2.1.0 includes the kklomega (lowRe) model for Reynoldsaverage 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 kw with an additional transport equation included to predict lowfrequency velocity fluctuations that trigger transition in the boundary layer. 

June 21, 2012, 10:05 

#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 

#36  
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Daniel WEI (老魏)
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Quote:
__________________
~ Daniel WEI  NatHaz Modeling Laboratory Department of Civil & Environmental Engineering & Earth Sciences University of Notre Dame, USA Email  My Personal CFD Blog 

June 21, 2012, 22:32 

#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?


June 22, 2012, 02:01 

#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. 

June 22, 2012, 12:20 

#40 
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Joe
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