how to set up wall function in bubbleFoam

adouchihiitoko · October 17, 2010, 03:05

Hi
I try to calculate turbulent bubbly flow by bubbleFoam. I don't know how to set up wall function in k and epsilon file in 0 folder since "bubbleColumn" tutorial doesn't treat turbulent flow and wall function. I suppose that "zeroGradient" is unreasonable. Can anyone help me?

alberto · October 18, 2010, 14:51

Please, check the code. Wall-functions in bubbleFoam are coded directly in the solver and automatically applied when the turbulence model is active.

Best,

adouchihiitoko · October 24, 2010, 04:16

Thanks.
I found all files related turbulence e.g. wallfunctions.* are in \applications\solvers\multiohase\bubbleFoam.

Franz_J · November 4, 2010, 08:18

Hi Adouchihihiitoko
Did you manage to get bubbleFoam to solve with turbulence as the RASModel ? I get the following messages,

keyword laplacian(DepsilonEff,epsilon) is undefined in dictionary "/home/f/OpenFOAM/f-1.7.0/working2/sludge2D/test2/system/fvSchemes::laplacianSchemes"

file: /home/f/OpenFOAM/f-1.7.0/working2/test2/system/fvSchemes::laplacianSchemes from line 42 to line 45.

From function dictionary::lookupEntry(const word&, bool, bool) const
in file db/dictionary/dictionary.C at line 395.

l_r_mcglashan · November 4, 2010, 08:57

Just add the entry into system/fvSchemes, and be careful using the turbulence model, it's very basic! Remember it's not using the turbulence libraries that can be used for single phase flows, so the only entry it uses in the RAS dictionary is turbulence on/off.

If you look in kEpsilon.H:

Code:

    // Dissipation equation
    fvScalarMatrix epsEqn
    (
        fvm::ddt(beta, epsilon)
      + fvm::div(phib, epsilon)
      - fvm::laplacian
        (
            alphaEps*nuEffb, epsilon,
            "laplacian(DepsilonEff,epsilon)"
        )
      ==
         C1*beta*G*epsilon/k
       - fvm::Sp(C2*beta*epsilon/k, epsilon)
    );

You can see that for the laplacian discretisation the scheme is looked up in the fvSchemes dictionary.

Franz_J · November 5, 2010, 06:59

thanks Laurence
I did that and it's working. Now I'm running some test cases and it crashes after abut 50 time steps, Ur Courant number tends to diverge, but I can fiddle with it,
thanks again

October 17, 2010, 03:05	how to set up wall function in bubbleFoam	#1
adouchihiitoko New Member trister Join Date: May 2009 Posts: 3 Rep Power: 6	Hi I try to calculate turbulent bubbly flow by bubbleFoam. I don't know how to set up wall function in k and epsilon file in 0 folder since "bubbleColumn" tutorial doesn't treat turbulent flow and wall function. I suppose that "zeroGradient" is unreasonable. Can anyone help me?

October 18, 2010, 14:51		#2
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,878 Rep Power: 23	Please, check the code. Wall-functions in bubbleFoam are coded directly in the solver and automatically applied when the turbulence model is active. Best, __________________ Alberto GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as live DVD/USB, hard drive image and virtual image. GeekoCFD 32bit - The 32bit edition of GeekoCFD. GeekoCFD text mode - A smaller version of GeekoCFD, text-mode only, with only OpenFOAM. Available in a variety of virtual formats.

November 4, 2010, 08:57		#5
l_r_mcglashan Senior Member Laurence R. McGlashan Join Date: Mar 2009 Posts: 346 Rep Power: 12	Just add the entry into system/fvSchemes, and be careful using the turbulence model, it's very basic! Remember it's not using the turbulence libraries that can be used for single phase flows, so the only entry it uses in the RAS dictionary is turbulence on/off. If you look in kEpsilon.H: Code: // Dissipation equation fvScalarMatrix epsEqn ( fvm::ddt(beta, epsilon) + fvm::div(phib, epsilon) - fvm::laplacian ( alphaEpsnuEffb, epsilon, "laplacian(DepsilonEff,epsilon)" ) == C1betaGepsilon/k - fvm::Sp(C2betaepsilon/k, epsilon) ); You can see that for the laplacian discretisation the scheme is looked up in the fvSchemes dictionary. __________________ Laurence R. McGlashan :: Website

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October 24, 2010, 04:16		#3
adouchihiitoko New Member trister Join Date: May 2009 Posts: 3 Rep Power: 6	Thanks. I found all files related turbulence e.g. wallfunctions.* are in \applications\solvers\multiohase\bubbleFoam.

November 4, 2010, 08:18		#4
Franz_J New Member Franz Jacobsen Join Date: Oct 2009 Location: Brisbane Posts: 4 Rep Power: 5	Hi Adouchihihiitoko Did you manage to get bubbleFoam to solve with turbulence as the RASModel ? I get the following messages, keyword laplacian(DepsilonEff,epsilon) is undefined in dictionary "/home/f/OpenFOAM/f-1.7.0/working2/sludge2D/test2/system/fvSchemes::laplacianSchemes" file: /home/f/OpenFOAM/f-1.7.0/working2/test2/system/fvSchemes::laplacianSchemes from line 42 to line 45. From function dictionary::lookupEntry(const word&, bool, bool) const in file db/dictionary/dictionary.C at line 395.

November 5, 2010, 06:59		#6
Franz_J New Member Franz Jacobsen Join Date: Oct 2009 Location: Brisbane Posts: 4 Rep Power: 5	thanks Laurence I did that and it's working. Now I'm running some test cases and it crashes after abut 50 time steps, Ur Courant number tends to diverge, but I can fiddle with it, thanks again