
[Sponsors] 
January 24, 2012, 10:13 

#21 
Senior Member
Daniel WEI (老魏)
Join Date: Mar 2009
Location: Beijing, China
Posts: 689
Blog Entries: 9
Rep Power: 13 
Actually, I tried yesterday night for a few times, but got a worse curve.
__________________
~ Daniel WEI  Boeing Research & Technology  China Beijing, China 

January 24, 2012, 20:15 

#22  
Senior Member
Sandy Lee
Join Date: Mar 2009
Posts: 213
Rep Power: 10 
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 
New Member
Luca Bonfiglio
Join Date: Oct 2011
Posts: 9
Rep Power: 6 
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  
Senior Member
Daniel WEI (老魏)
Join Date: Mar 2009
Location: Beijing, China
Posts: 689
Blog Entries: 9
Rep Power: 13 
Quote:
mesh and then everything works fine. It seems all LRN models have convergence problem.
__________________
~ Daniel WEI  Boeing Research & Technology  China Beijing, China 

April 11, 2012, 18:07 

#25 
New Member
Luca Bonfiglio
Join Date: Oct 2011
Posts: 9
Rep Power: 6 
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 
New Member
Join Date: Feb 2012
Posts: 2
Rep Power: 0 
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 
New Member
Tom Li
Join Date: Aug 2011
Posts: 16
Rep Power: 7 
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 
New Member
Join Date: Feb 2012
Posts: 2
Rep Power: 0 
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  
Senior Member
Sandy Lee
Join Date: Mar 2009
Posts: 213
Rep Power: 10 
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 
New Member
Tom Li
Join Date: Aug 2011
Posts: 16
Rep Power: 7 
Thanks Sandy and Vahini
I guess I missed the obvious part in the model lol 

April 27, 2012, 08:52 

#31 
Member
Join Date: Jun 2011
Posts: 38
Rep Power: 7 
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 
New Member
Titus van den Brink
Join Date: Apr 2009
Location: breda netherlands
Posts: 17
Rep Power: 9 
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 
Senior Member
Sandy Lee
Join Date: Mar 2009
Posts: 213
Rep Power: 10 
what is the "new kklomega model " ?


May 7, 2012, 03:19 

#34 
New Member
Titus van den Brink
Join Date: Apr 2009
Location: breda netherlands
Posts: 17
Rep Power: 9 
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 
Senior Member
Mads Reck
Join Date: Aug 2009
Location: Copenhagen, Denmark
Posts: 175
Rep Power: 10 
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
__________________
Online free airfoilmesher for OpenFOAM here 

June 21, 2012, 10:21 

#36  
Senior Member
Daniel WEI (老魏)
Join Date: Mar 2009
Location: Beijing, China
Posts: 689
Blog Entries: 9
Rep Power: 13 
Quote:
__________________
~ Daniel WEI  Boeing Research & Technology  China Beijing, China 

June 21, 2012, 22:32 

#38 
Member
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 6 
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 
New Member
RDG
Join Date: Feb 2011
Posts: 29
Rep Power: 7 
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 
Member
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 6 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Superlinear speedup in OpenFOAM 13  msrinath80  OpenFOAM Running, Solving & CFD  18  March 3, 2015 06:36 
Turbulence model for low Reynolds number flow?  Nokadu  Main CFD Forum  3  May 26, 2013 11:42 
Centrifugal Pump and Turbulence Model  Michiel  CFX  12  January 25, 2010 04:20 
turbulence model equation  Andy Chen  FLOW3D  4  January 1, 2010 22:45 
build your own turbulence model with buoyancy  Thomas Baumann  OpenFOAM  11  November 23, 2009 09:53 