Yplus and ystar

guido_adriaensen · September 4, 2006, 09:22

Hello,

I was taking a look at the calculation of y-plus with the checkYPlus utility, but isn't this in fact a check for y-star?

Y-star = rho*Cmu^0.25*sqrt(k)*y/mu
y-plus = rho*sqrt(tau_w/rho_w)*y/mu

Thus Y-star is related to the turbulent kinetic energy and y-plus to the wallshearstress, or am I now overlooking something?

kind regards
Guido

svens · September 9, 2009, 14:49

Hey Guido

I'm running some calculations with RSTMs and while checking y+ for the first cell I recognized the same.

Checking via the yPlusRAS command creates totally different values than the calculation with:

y+ = Utau*y/nu with Utau = SQRT(Tau_wall/rho)

Meanwhile did you figured out something to avoid this curio?

Thanks and regards,
Sven

immortality · April 26, 2013, 10:03

although its old.but I have found that yPlusRAS uses y* furmula in return of y+.could anyone guide me or give an explanation on why?

Mojtaba.a · May 2, 2013, 11:40

Quote:

Originally Posted by immortality

although its old.but I have found that yPlusRAS uses y* furmula in return of y+.could anyone guide me or give an explanation on why?

Dear Ehsan,
Check out this post, Niklas has came up with a solution by modifying the file yPlusLES.C:

Problems with YPlusRAS and wallShearStress

best

immortality · May 2, 2013, 12:14

thanks Mojtaba.
but my case is compressible.do you know how to change the incompressible yPlus code?

and also it doesn't compile in OF 2.2.0:

Code:

ehsan@Ehsan-com:~/Desktop/yPlus$ wmake
Making dependency list for source file yPlus.C
could not open file basicPsiThermo.H for source file yPlus.C
SOURCE=yPlus.C ;  g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3  -DNoRepository -ftemplate-depth-100 -I/opt/openfoam220/src/meshTools/lnInclude -I/opt/openfoam220/src/transportModels -I/opt/openfoam220/src/turbulenceModels -I/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions -I/opt/openfoam220/src/turbulenceModels/compressible/RAS/derivedFvPatchFields/wallFunctions/mutWallFunctions -I/opt/openfoam220/src/thermophysicalModels/basic/lnInclude -I/opt/openfoam220/src/finiteVolume/lnInclude -IlnInclude -I. -I/opt/openfoam220/src/OpenFOAM/lnInclude -I/opt/openfoam220/src/OSspecific/POSIX/lnInclude   -fPIC -c $SOURCE -o Make/linux64GccDPOpt/yPlus.o
yPlus.C:37:28: fatal error: basicPsiThermo.H: No such file or directory
compilation terminated.
make: *** [Make/linux64GccDPOpt/yPlus.o] Error 1

Mojtaba.a · May 2, 2013, 12:52

Quote:

Originally Posted by immortality

thanks Mojtaba.
but my case is compressible.do you know how to change the incompressible yPlus code?

and also it doesn't compile in OF 2.2.0:

Code:

ehsan@Ehsan-com:~/Desktop/yPlus$ wmake
Making dependency list for source file yPlus.C
could not open file basicPsiThermo.H for source file yPlus.C
SOURCE=yPlus.C ;  g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3  -DNoRepository -ftemplate-depth-100 -I/opt/openfoam220/src/meshTools/lnInclude -I/opt/openfoam220/src/transportModels -I/opt/openfoam220/src/turbulenceModels -I/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions -I/opt/openfoam220/src/turbulenceModels/compressible/RAS/derivedFvPatchFields/wallFunctions/mutWallFunctions -I/opt/openfoam220/src/thermophysicalModels/basic/lnInclude -I/opt/openfoam220/src/finiteVolume/lnInclude -IlnInclude -I. -I/opt/openfoam220/src/OpenFOAM/lnInclude -I/opt/openfoam220/src/OSspecific/POSIX/lnInclude   -fPIC -c $SOURCE -o Make/linux64GccDPOpt/yPlus.o
yPlus.C:37:28: fatal error: basicPsiThermo.H: No such file or directory
compilation terminated.
make: *** [Make/linux64GccDPOpt/yPlus.o] Error 1

I don't know how but maybe it is something like what Niklas did. modifying yPlusLES to be used for RAS for compressible flows.

Which file did you use to compile?

immortality · May 2, 2013, 13:25

the second file he has put there.are they only for LES?

Mojtaba.a · May 2, 2013, 13:44

Quote:

Originally Posted by immortality

the second file he has put there.are they only for LES?

I think you got to modify them in order to use them with RAS models.
the uploaded file is the utility I used for incompressible flows using RAS models.

immortality · May 2, 2013, 14:47

it gives this error.maybe it should modified for 2.2.0 version.

Code:

ehsan@Ehsan-com:~/Desktop/yPlus$ wmake
Making dependency list for source file yPlus.C
could not open file nutWallFunctionFvPatchScalarField.H for source file yPlus.C
could not open file basicPsiThermo.H for source file yPlus.C
could not open file mutWallFunctionFvPatchScalarField.H for source file yPlus.C
SOURCE=yPlus.C ;  g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3  -DNoRepository -ftemplate-depth-100 -I/opt/openfoam220/src/meshTools/lnInclude -I/opt/openfoam220/src/transportModels -I/opt/openfoam220/src/turbulenceModels -I/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions -I/opt/openfoam220/src/turbulenceModels/compressible/RAS/derivedFvPatchFields/wallFunctions/mutWallFunctions -I/opt/openfoam220/src/thermophysicalModels/basic/lnInclude -I/opt/openfoam220/src/finiteVolume/lnInclude -IlnInclude -I. -I/opt/openfoam220/src/OpenFOAM/lnInclude -I/opt/openfoam220/src/OSspecific/POSIX/lnInclude   -fPIC -c $SOURCE -o Make/linux64GccDPOpt/yPlus.o
In file included from yPlus.C:35:0:
/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions/nutkWallFunction/nutkWallFunctionFvPatchScalarField.H:56:47: fatal error: nutWallFunctionFvPatchScalarField.H: No such file or directory
compilation terminated.
make: *** [Make/linux64GccDPOpt/yPlus.o] Error 1

Mojtaba.a · May 2, 2013, 15:29

Quote:

Originally Posted by immortality

it gives this error.maybe it should modified for 2.2.0 version.

Code:

ehsan@Ehsan-com:~/Desktop/yPlus$ wmake
Making dependency list for source file yPlus.C
could not open file nutWallFunctionFvPatchScalarField.H for source file yPlus.C
could not open file basicPsiThermo.H for source file yPlus.C
could not open file mutWallFunctionFvPatchScalarField.H for source file yPlus.C
SOURCE=yPlus.C ;  g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3  -DNoRepository -ftemplate-depth-100 -I/opt/openfoam220/src/meshTools/lnInclude -I/opt/openfoam220/src/transportModels -I/opt/openfoam220/src/turbulenceModels -I/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions -I/opt/openfoam220/src/turbulenceModels/compressible/RAS/derivedFvPatchFields/wallFunctions/mutWallFunctions -I/opt/openfoam220/src/thermophysicalModels/basic/lnInclude -I/opt/openfoam220/src/finiteVolume/lnInclude -IlnInclude -I. -I/opt/openfoam220/src/OpenFOAM/lnInclude -I/opt/openfoam220/src/OSspecific/POSIX/lnInclude   -fPIC -c $SOURCE -o Make/linux64GccDPOpt/yPlus.o
In file included from yPlus.C:35:0:
/opt/openfoam220/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions/nutkWallFunction/nutkWallFunctionFvPatchScalarField.H:56:47: fatal error: nutWallFunctionFvPatchScalarField.H: No such file or directory
compilation terminated.
make: *** [Make/linux64GccDPOpt/yPlus.o] Error 1

Well, this is strange. I compiled for OF 2.1 and it worked fine.
There is no nutWallFunctionFvPatchScalarField.H inside yPlus.C that it can't find. instead nutkWallFunctionFvPatchScalarField.H is used. Are you sure you are using the file I uploaded?
I don't know if it has changed in OF 2.2 or not. maybe its dependency issues.

immortality · May 3, 2013, 07:55

yes.I use that file.
can anyone help how change it to adapt to 2.2.0 version?

immortality · May 5, 2013, 08:44

in mutkWallFunctionFvPatchScalarField the equation uses for y-plus is related to y-star not y-plus

Code:

Code:

y-star=pow(0.09,0.25)*sqr(k)*nearDist()/mu

Code:

y-plus=rho*u_star*y/mu which u*=aqrt(taw_w/rho)

y-star is related to turbulent kinetic energy while y-plus relates to friction velocity(that relates to wall skin friction in its own)

in the code of mut
:
Code:

Code:

forAll(mutw, faceI)     {         label faceCellI = patch().faceCells()[faceI];          scalar yPlus =             Cmu25*y[faceI]*sqrt(k[faceCellI])/(muw[faceI]/rhow[faceI]);          if (yPlus > yPlusLam_)         {             mutw[faceI] = muw[faceI]*(yPlus*kappa_/log(E_*yPlus) - 1);         }     }

thanks.

immortality · May 5, 2013, 13:41

could anyone have a look to resolve the error?

Code:

ehsan@Ehsan-com:~/Desktop/yPlus$ wmake
/bin/sh: /home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/wmake/bin/linux64Gcc/wmkdep: not found
SOURCE=yPlus.C ;  g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3  -DNoRepository -ftemplate-depth-40 -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/meshTools/lnInclude -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/transportModels -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/turbulenceModels -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/turbulenceModels/compressible/RAS/derivedFvPatchFields/wallFunctions/mutWallFunctions -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/thermophysicalModels/basic/lnInclude -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/finiteVolume/lnInclude -IlnInclude -I. -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/OpenFOAM/lnInclude -I/home/ehsan/OpenFOAM/OpenFOAM-1.6-ext/src/OSspecific/POSIX/lnInclude   -fPIC -c $SOURCE -o Make/linux64GccDPOpt/yPlus.o
yPlus.C:32:19: fatal error: fvCFD.H: No such file or directory
compilation terminated.
make: *** [Make/linux64GccDPOpt/yPlus.o] Error 1

September 4, 2006, 09:22	Hello, I was taking a look	#1
guido_adriaensen Member Guido Adriaensen Join Date: Mar 2009 Posts: 56 Rep Power: 6	Hello, I was taking a look at the calculation of y-plus with the checkYPlus utility, but isn't this in fact a check for y-star? Y-star = rhoCmu^0.25sqrt(k)y/mu y-plus = rhosqrt(tau_w/rho_w)*y/mu Thus Y-star is related to the turbulent kinetic energy and y-plus to the wallshearstress, or am I now overlooking something? kind regards Guido

September 9, 2009, 14:49		#2
svens Member Sven Schweikert Join Date: Jun 2009 Posts: 38 Rep Power: 5	Hey Guido I'm running some calculations with RSTMs and while checking y+ for the first cell I recognized the same. Checking via the yPlusRAS command creates totally different values than the calculation with: *y+ = Utauy/nu with Utau = SQRT(Tau_wall/rho)** Meanwhile did you figured out something to avoid this curio? Thanks and regards, Sven immortality likes this.

May 5, 2013, 08:44		#12
immortality Banned ehsan Join Date: Oct 2012 Location: Iran Posts: 1,106 Rep Power: 0	in mutkWallFunctionFvPatchScalarField the equation uses for y-plus is related to y-star not y-plus Code: Code: y-star=pow(0.09,0.25)sqr(k)nearDist()/mu Code: Code: y-plus=rhou_stary/mu which u=aqrt(taw_w/rho) y-star is related to turbulent kinetic energy while y-plus relates to friction velocity(that relates to wall skin friction in its own) in the code of mut : Code: Code: forAll(mutw, faceI) { label faceCellI = patch().faceCells()[faceI]; scalar yPlus = Cmu25y[faceI]sqrt(k[faceCellI])/(muw[faceI]/rhow[faceI]); if (yPlus > yPlusLam_) { mutw[faceI] = muw[faceI](yPluskappa_/log(E_yPlus) - 1); } } thanks.

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April 26, 2013, 10:03		#3
immortality Banned ehsan Join Date: Oct 2012 Location: Iran Posts: 1,106 Rep Power: 0	although its old.but I have found that yPlusRAS uses y* furmula in return of y+.could anyone guide me or give an explanation on why?

May 2, 2013, 13:25		#7
immortality Banned ehsan Join Date: Oct 2012 Location: Iran Posts: 1,106 Rep Power: 0	the second file he has put there.are they only for LES?

May 3, 2013, 07:55		#11
immortality Banned ehsan Join Date: Oct 2012 Location: Iran Posts: 1,106 Rep Power: 0	yes.I use that file. can anyone help how change it to adapt to 2.2.0 version?