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IDProjectCategoryView StatusLast Update
0001564OpenFOAM[All Projects] Bugpublic2015-03-13 12:06
ReporterprojectionistAssigned Tohenry 
PrioritynormalSeveritytrivialReproducibilityalways
Status resolvedResolutionfixed 
PlatformGNU/LinuxOSUbuntuOS Version14.10
Product Version 
Fixed in Version 
Summary0001564: [Tomiyama Lift Model] minor differences between reference and implementation
DescriptionI noticed in the file TomiyamaLift.C there are some minor differences between the paper, which is referred to in the header file, and the actual implementation.

The return statement of the method Cl() reads:

return
        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10))*f
      + pos(EoH - scalar(10))*(-0.29);

However, if I compare this with Equation (10) of the paper, it should read:

return
        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10.7))*f
      + pos(EoH - scalar(10.7))*(-0.288);
TagsNo tags attached.

Activities

projectionist

2015-03-10 18:24

reporter   ~0004073

In addition I would like to ask a question.

In phasePair.C the methods EoH1() and EoH2() call the method EoH() for computing the Eotvos number. Both methods compute the hydraulic diameter by dividing the diameter of the dispersed phase (dispersed_.d()) by the cubic-root of the aspect ratio.

My question is: what is the rationale behind using the cubic-root of the aspect ratio?

Sorry, for abusing the notes on the bug for an off-topic question.

Keep up the great work!

henry

2015-03-10 20:08

manager   ~0004075

Thanks for checking the implementation against the original paper. I only have subseqent papers in which the coefficients are slightly different.

Resolved by commit 1f187d6f9e58c232a1363aafe4ffe46e6f20f876

I don't know the rationale behind using the cubic-root of the aspect ratio, I would need to dig-up the papers to see if it stated there. Someone else may be able to provide you with more information on this but this bug reporting system is not the right forum for these discussions.

henry

2015-03-11 09:41

manager   ~0004076

Reopened to allow others to comment

Juho

2015-03-11 10:00

reporter   ~0004077

The difference between the EoH1() and EoH2() is that the 2 applies user selected aspect ratio model to calculate the hydraulic diameter, while 1 uses a hard coded Wellek model for the aspect ratio.

Another slight variation of the Tomiyama lift model is used in CFX where they have modified the coefficients to make the correlation continuous: http://www.drthfrank.de/publications/2004/Shi_Frank_ICMF_2004_final.pdf

        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10))*f
      + pos(EoH - scalar(10))*(-0.27);

As shown in the attached image, other continuous variations more similar to the original paper could be:

        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10))*f
      + pos(EoH - scalar(10.7))*(-0.2784);

or

volScalarField f(0.0010422*pow3(EoH) - 0.0159*sqr(EoH) - 0.0204*EoH + 0.474);

        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10))*f
      + pos(EoH - scalar(10.7))*(-0.288);

I would perhaps prefer the last one, but there is no reference for the last two variations.

Juho

2015-03-11 10:00

reporter  

TomiyamaLift.png (5,784 bytes)
TomiyamaLift.png (5,784 bytes)

henry

2015-03-11 10:16

manager   ~0004078

I am happy to put in the form of the model your propose but it would be useful to add some text to justify the changes to the coefficients from the original paper. Could you provide the rationale that could be added to the header?

Juho

2015-03-11 11:17

reporter   ~0004080

Note that there's a typo in the variations I posted above. The upper limit mid EoH part should of course match the lower limit of the high EoH part

i.e.

volScalarField f(0.0010422*pow3(EoH) - 0.0159*sqr(EoH) - 0.0204*EoH + 0.474);

        neg(EoH - scalar(4))*min(0.288*tanh(0.121*pair_.Re()), f)
      + pos(EoH - scalar(4))*neg(EoH - scalar(10.7))*f
      + pos(EoH - scalar(10.7))*(-0.288);

The rationale for the header could be something like: "The coefficient for pow3(EoH) proposed by Tomiyama (2002) has been modified to make the model continuous at EoH = 10.7 while maintaining the lift coefficient proposed by Tomiyama (2002) when EoH >= 10.7."

henry

2015-03-11 18:10

manager   ~0004089

Thanks Juho, I have applied your correction.

Issue History

Date Modified Username Field Change
2015-03-10 18:02 projectionist New Issue
2015-03-10 18:24 projectionist Note Added: 0004073
2015-03-10 20:08 henry Note Added: 0004075
2015-03-10 20:08 henry Status new => resolved
2015-03-10 20:08 henry Resolution open => fixed
2015-03-10 20:08 henry Assigned To => henry
2015-03-11 09:41 henry Note Added: 0004076
2015-03-11 09:41 henry Status resolved => feedback
2015-03-11 09:41 henry Resolution fixed => reopened
2015-03-11 10:00 Juho Note Added: 0004077
2015-03-11 10:00 Juho File Added: TomiyamaLift.png
2015-03-11 10:16 henry Note Added: 0004078
2015-03-11 11:17 Juho Note Added: 0004080
2015-03-11 18:10 henry Note Added: 0004089
2015-03-11 18:10 henry Status feedback => resolved
2015-03-11 18:10 henry Resolution reopened => fixed
2015-03-24 00:17 liuhuafei Issue cloned: 0001617