CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

[OpenFOAM-2.1.0] kklOmega RAS Turbulence Model (low Re)

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree7Likes

Reply
 
LinkBack Thread Tools Display Modes
Old   June 24, 2012, 10:05
Default
  #41
Member
 
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 5
jferrari is on a distinguished road
Link to my case: https://www.dropbox.com/sh/s555kq1drmm0c2j/pgpJnsuMca

screenshot of kl:


Should there be a spike in kl as it's leaving the domain? nut shows similar behavior, but the kt and omega fields seem to be fine.

The only reason I'm questioning these results is because the lift coefficient is lower than published. The flow fields behave similarly at 11 and 9 degrees angle of attack, but the lift coefficient is much closer.

All information is in the case folder I posted - Does anyone see where my error is?

Thanks
jferrari is offline   Reply With Quote

Old   June 25, 2012, 12:23
Default
  #42
Member
 
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 5
jferrari is on a distinguished road
Quote:
Originally Posted by jferrari View Post
Does anyone see where my error is?
I'm not even sure if it's an error - the laminar kinetic energy might just behave like that....
jferrari is offline   Reply With Quote

Old   June 26, 2012, 20:04
Default
  #43
Member
 
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 5
jferrari is on a distinguished road
I'm getting more convinced that something is wrong - having paraview smooth over the results was misleading. When I have paraview display the values for each volume, there are two cells at the extremities of the domain where nut and kl are significantly greater than anywhere else in the domain. Walters suggests boundary conditions for kl, kt, and omega in his paper, but no guidance on nut - so I set it to zeroGradient at the wall and inletOutlet at the farfield with inletValue equal to

CmuStd*kt/omega

based on the cfd-online wiki article on farfield boundary conditions.

I'm going to try fixedValue instead of inletOutlet. I'll update when the run finishes.
jferrari is offline   Reply With Quote

Old   July 2, 2012, 12:19
Default
  #44
Member
 
Joe
Join Date: Dec 2011
Location: Groton, CT
Posts: 67
Rep Power: 5
jferrari is on a distinguished road
Using the fixedValue boundary condition for nut seemed to fix things.
jferrari is offline   Reply With Quote

Old   July 28, 2012, 01:15
Default plz help me
  #45
Member
 
vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 80
Rep Power: 4
vahid.najafi is an unknown quantity at this point
Hi,Dear foamers.
I'm working with openFoam 2.0.1,and have a problem with solver (interPhaseChangeFoam) in multiphase solvers.
my friends tell me, you can help me.
I have add (turbulence kinetic Energy or k ) in a part of this solver.
first:
added:
-I$(LIB_SRC)/turbulenceModels \
-I$(LIB_SRC)/turbulenceModels/incompressible/RAS/RASModel \

in option.


and then:
added
//.................................................. .....changed
// Construct incompressible turbulence model
autoPtr<incompressible::RASModel> turbulence
(
incompressible::RASModel::New(U, phi, twoPhaseProperties())
);
//.................................................. .....changed


in creatField.

and then:
added

#include "RASModel.H"
and:

//.................................................. .............
volScalarField turbKinEnergy = turbulence().k(); //turbKinEnergy = turbulence().k();
volScalarField turbDisEnergy = turbulence().epsilon();
in this and turbkinEnergy=k
//.................................................. .............


in myinterPhaseChangeFoam.c

and wmake is ok!!!



but
I want in this solver in directory:
/run/myinterPhaseChangeFoam/phaseChangeTwoPhaseMixtures/SchnerrSauer/SchnerrSauer.c




I added
#include "RASModel.H"

in it and:


Foam::tmp<Foam::volScalarField>
Foam:haseChangeTwoPhaseMixtures::SchnerrSauer: Coeff
(
const volScalarField& p
) const
{
volScalarField limitedAlpha1(min(max(alpha1_, scalar(0)), scalar(1)));
volScalarField rho
(
limitedAlpha1*rho1() + (scalar(1) - limitedAlpha1)*rho2()
);

return
//......I want to change it( <<k>> turbulence multiple in it):
(3*rho1()*rho2())*sqrt(2/(3*rho1()))*k()
*rRb(limitedAlpha1)/(rho*sqrt(mag(p - pSat()) + 0.01*pSat()));
//.................................................. ......
}


dont successful wmake, and seen(was not declared ):

I/opt/openfoam201/src/OSspecific/POSIX/lnInclude -fPIC -c $SOURCE -o Make/linux64GccDPOpt/SchnerrSauer.o
phaseChangeTwoPhaseMixtures/SchnerrSauer/SchnerrSauer.C: In member function â€کFoam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam:haseChangeTwoPhaseMixtures::SchnerrSauer: Coeff(const Foam::volScalarField&) const’:
phaseChangeTwoPhaseMixtures/SchnerrSauer/SchnerrSauer.C:113: error: k() was not declared in this scope
make: *** [Make/linux64GccDPOpt/SchnerrSauer.o] Error 1


please help me.
vahid.najafi is offline   Reply With Quote

Old   July 28, 2012, 22:55
Default
  #46
Senior Member
 
Sandy Lee
Join Date: Mar 2009
Posts: 207
Rep Power: 9
sandy is on a distinguished road
Hi, I think, maybe you need not add
#include "RASModel.H"

However, maybe you need to make code find out k() by
const volScalarField &k=U_.db().lookupObject<volScalarField>("k");

namely
Foam::tmp<Foam::volScalarField>
Foam:haseChangeTwoPhaseMixtures::SchnerrSauer: Coeff
(
const volScalarField& p
) const
{
volScalarField limitedAlpha1(min(max(alpha1_, scalar(0)), scalar(1)));
volScalarField rho
(
limitedAlpha1*rho1() + (scalar(1) - limitedAlpha1)*rho2()
);

return
const volScalarField &k=U_.db().lookupObject<volScalarField>("k");

(3*rho1()*rho2())*sqrt(2/(3*rho1()))*k()
*rRb(limitedAlpha1)/(rho*sqrt(mag(p - pSat()) + 0.01*pSat()));
sandy is offline   Reply With Quote

Old   July 29, 2012, 01:23
Default an other question
  #47
Member
 
vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 80
Rep Power: 4
vahid.najafi is an unknown quantity at this point
Hi Dear Sandy Lee.
Thanks alot for your answer.its wmake Successfully.

but How can I Understand that this k is the same with k(kinetic turbulence energy)???

Because I replase another word in this :

const volScalarField &M=U_.db().lookupObject<volScalarField>("M")

but not error occured!!!!!!??????

Last edited by vahid.najafi; July 29, 2012 at 02:14.
vahid.najafi is offline   Reply With Quote

Old   July 29, 2012, 09:38
Default
  #48
Senior Member
 
Sandy Lee
Join Date: Mar 2009
Posts: 207
Rep Power: 9
sandy is on a distinguished road
Hi, I just give you an example, however, you still need to find what is the correct expression of kinetic turbulence energy in RASModel.H or RASModel.C ...
sandy is offline   Reply With Quote

Old   July 29, 2012, 10:50
Default Thanks
  #49
Member
 
vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 80
Rep Power: 4
vahid.najafi is an unknown quantity at this point
Thanks for your answer sandy!!!your answer is true !!!
Thank you so much...

Last edited by vahid.najafi; July 29, 2012 at 11:29.
vahid.najafi is offline   Reply With Quote

Old   July 30, 2012, 05:43
Default Hi
  #50
Member
 
vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 80
Rep Power: 4
vahid.najafi is an unknown quantity at this point
Hi again dear Sandi.
If you Let me,I request you ,answer me an other question???
I promise this is Final question:

I want to add surface tension(sigma) in one solver,for this reason I added:
#include ''fvCFD.H''
#include ''interfaceProperties.H''

because sigma defined in <interfaceProperties.H> .
location this file(interfaceProperties) in directory:src->interfaceProperties .
and then added next line for Definition this parameter:
fvc::interpolate(interface.sigma())
but I seen again this error:
'interface' was not declared in this scope!!!
Thank you very much

Last edited by vahid.najafi; July 30, 2012 at 05:59.
vahid.najafi is offline   Reply With Quote

Old   January 30, 2013, 06:58
Default
  #51
Member
 
s.rasoul_varedi
Join Date: Feb 2010
Posts: 82
Rep Power: 6
desert_1250 is an unknown quantity at this point
Send a message via Yahoo to desert_1250
Hi foamers
I wanna simulate flow over S809 airfoil using new turbulace model nominated "kklOmega" for 0 to 24 angles of attacks to predict stall and post stall. the solver that i used, is pimpleFoam, but the solution diverged despite i applied very low time step.
would you please help me how to apply this transitoin model?
Best/ Rasoul
vahid.najafi likes this.
desert_1250 is offline   Reply With Quote

Old   January 30, 2013, 09:06
Default dear rasoul
  #52
Member
 
vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 80
Rep Power: 4
vahid.najafi is an unknown quantity at this point
Hi, my dear friend.
Courant Number=c.delta(t)/delta(x) and it must be < 1.
Sometimes apply very low time step is not true.
I guess if you Get larger mesh your solution is Convergent.

Good Luck
vahid.najafi is offline   Reply With Quote

Old   January 31, 2013, 00:11
Default
  #53
Member
 
s.rasoul_varedi
Join Date: Feb 2010
Posts: 82
Rep Power: 6
desert_1250 is an unknown quantity at this point
Send a message via Yahoo to desert_1250
hello dear vahid
1-it is abvious that C Number must be below 1 even 0.2. this is applied by default.
2-time step is controlled using adjustableRunTime utility.
3-if the coarse mesh has been used then must be expected that the result is'nt accurate. also i think that need to supply fine mesh to predict low-frequency velocity fluctuations in the boundary layer.
BTW i used neither coarse nor fine mesh and also several meshes are applied for this subject. but the convergency of the solution is still a challenge!!!
tnx/Rasoul
desert_1250 is offline   Reply With Quote

Old   March 12, 2013, 11:23
Default
  #54
Senior Member
 
sfigato's Avatar
 
Marco Longhitano
Join Date: Jan 2013
Location: Aachen
Posts: 103
Rep Power: 4
sfigato is on a distinguished road
Send a message via Skype™ to sfigato
Hallo Foamers,

i have exactely the same vahid's problem:
Quote:

Member

vahid
Join Date: Feb 2012
Location: Mashhad-Iran
Posts: 79
Rep Power: 2


Hi,Dear foamers.
I'm working with openFoam 2.0.1,and have a problem with solver (interPhaseChangeFoam) in multiphase solvers.
my friends tell me, you can help me.
I have add (turbulence kinetic Energy or k ) in a part of this solver.

I want to call for the turbulence kinetic energy to interPhaseChangeFoam. I want to use it in the SchnerrSauer.c model!
I have done a lot of trials without any sucssefull compiling!

Can anyone help me??

Best Regards
Marco
sfigato is offline   Reply With Quote

Old   April 8, 2013, 20:05
Default
  #55
New Member
 
Jialin Su
Join Date: Mar 2013
Location: Loughborough
Posts: 29
Rep Power: 4
callumso is on a distinguished road
I think probably I can answer this question. Whether it is gonna be bypass or natural transistion depends on the turbulence level (or turbulence intensity to be more precise) of the free stream flow. When the turbulence intensity is low, the laminar flow goes through the Tollmien-Schlichting waves and eventually developes into fully turbulent flow, and this is the natural transition. When the turbulence level is high, the TS stage will be bypassed before the flow becomes fully turbulent, and the so-called bypass transistion. This is the understanding I gained when I did flow control to suppress transistion caused by free stream disturbance.
But please feel free to correct me if anyone has a more correct understanding.
callumso is offline   Reply With Quote

Old   August 27, 2013, 15:16
Default
  #56
Senior Member
 
Mojtaba.a's Avatar
 
Mojtaba Amiraslanpour
Join Date: Jun 2011
Location: Zanjan, Iran
Posts: 233
Rep Power: 7
Mojtaba.a is on a distinguished road
Send a message via Yahoo to Mojtaba.a
Dear all,

Thank you for all the suggestions. Very great thread.

Can you please help me setup my first low-Re turbulence case?

When I use kkLOmega model i get the following error:

Quote:
--> FOAM FATAL ERROR:

request for volScalarField k from objectRegistry region0 failed
available objects of type volScalarField are

29
(
((((1-exp((-sqrt((((sqr((min((Clambda*y),(sqrt((kt+kl))|(omega +omegaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMA LL)))*kt)|nu)|(omega+omegaMin)))|Av)))*CmuStd)*sqr t(((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+k Min))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+ome gaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)) )*kt)))*min((Clambda*y),(sqrt((kt+kl))|(omega+omeg aMin))))
(kt-((exp(-sqr((((Css*nu)*(1.41421*mag(skew(grad(U)))))|(kt+k Min))))*(min((Clambda*y),(sqrt((kt+kl))|(omega+ome gaMin)))|((sqrt((kt+kl))|(omega+omegaMin))+SMALL)) )*kt))
kt_0
nut
kt
.
.
.
Can anybody please share a sample case for this purpose?

None of the above links works.

Thank you,
Mojtaba
__________________
Complex Heat & Flow Simulation Research Group
If you can't explain it simply, you don't understand it well enough. "Richard Feynman"
Mojtaba.a is offline   Reply With Quote

Old   February 17, 2014, 08:48
Default
  #57
Member
 
Ye Zhang
Join Date: Dec 2009
Location: Delft,Netherland
Posts: 91
Rep Power: 7
kiddmax is on a distinguished road
Dear Titus,

Did you have good results for 3D transition simulation with kklomega model?
I am also doing 3D blades simulation with this model, but have converged problem. laminar kinematic energy always crashed. Can you give me some hint ?

Best regards,
Ye
kiddmax is offline   Reply With Quote

Old   February 19, 2014, 05:52
Default
  #58
Member
 
Ye Zhang
Join Date: Dec 2009
Location: Delft,Netherland
Posts: 91
Rep Power: 7
kiddmax is on a distinguished road
Dear wei,

I know this is quite old thread, but currently I am also using this kkLOmega transition model and hope maybe you can give me some help based on your experience.

Now I am using steady solver 'simpleFoam' to simulate. I have tried this model for external flow simulation for 2D airfoil and it works good, I would say. When I turn to 3D twisted blade, the solution always diverges after several iterations. Firstly kl becomes quite large then kt have the same trend. I have tried several div Schemes but they do not help. Do you think is it to limit kl and kt between some ranges? for example use limitedVanLeer 0 1 for div scheme? I have tried that, but also failed.

Anyway, any suggestions will be welcomed !!

Thank you

Best regards,
Ye
kiddmax is offline   Reply With Quote

Old   February 19, 2014, 05:54
Default
  #59
Member
 
Ye Zhang
Join Date: Dec 2009
Location: Delft,Netherland
Posts: 91
Rep Power: 7
kiddmax is on a distinguished road
Best regards,
Ye
kiddmax is offline   Reply With Quote

Old   June 12, 2014, 13:31
Default
  #60
Senior Member
 
M. Montero
Join Date: Mar 2009
Location: Madrid
Posts: 112
Rep Power: 8
be_inspired is on a distinguished road
Anyone,

could please share a simple test case about this turbulence model or could revise me test case?
https://drive.google.com/folderview?...VE&usp=sharing
I want to simulate a 2D airfoil using simpleFoam. The mesh is y+ around 1 so no wall functions are needed.
U=50m/s
TI=1%
lenght scale=0.2m
I have used GroovyBC to impose a fixedValue if flow comes in and zeroGradient if the flow goes out.
Without turbulence of using SA, all works correctly but not with kklomega.
k=kt=0.375 for internal Field
k=kt=0.375 if inlet and zeroGradient if outlet
k=kt=0 for wall
kl=0 for internal Field, patches and wall
omega=zeroGradient at wall
omega=3 for inlet and zeroGradient for outlet

Thank you very much

UPDATED: Using upwind no problem it run ( not so good results), using a linear scheme, it cracks.

Last edited by be_inspired; June 13, 2014 at 10:11.
be_inspired is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


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 FLOW-3D 4 January 1, 2010 22:45
build your own turbulence model with buoyancy Thomas Baumann OpenFOAM 11 November 23, 2009 09:53


All times are GMT -4. The time now is 06:51.