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IDProjectCategoryView StatusLast Update
0000764OpenFOAMBugpublic2015-01-29 09:49
Reporteruser584Assigned Tohenry  
PrioritynormalSeverityminorReproducibilityalways
Status closedResolutionno change required 
OSUbuntuOS Version204.1 LTS 
Summary0000764: Worng evaulation of laminar viscosity nu() in cavitatingFoam
DescriptionI've tried to solve a cavitating flow by using cavitatingFoam.
Until now, it always crashes --.

When checking the code, I found one thing, which seems a bug!
In cavitatingFoam, nu() seems to be calculated by using "twoPhaseMixture" class.
"twoPhaseMixture" class reads transportProperties and returns nu() to turbulence.
Anyway, in twoPhaseMixture, nu() value depends on "alpha".
In this case, alpha=1 means pure liquid, alpha=0 does pure gas for example.
In the case of cavitatingFoam, however, gamma=0 represents for pure liquid.

What I mean is that alpha and gamma has exactly different meaning.

When I checked nu() field for tutorial "trottle", surely worng nu() values could be obtained.
Gas viscosity values exist in the region of gamma=0 (pure liquid).

I always appreciate your efforts!

Thanks in advance.

Scurry
TagsNo tags attached.

Activities

henry

2013-03-05 16:53

manager   ~0001956

twoPhaseMixture does not make any assumptions about which phase is gas and which is liquid, in fact they could both be gas or both liquid. The phase properties for each phase are set in the transportProperties dictionary.

user584

2013-03-06 09:24

  ~0001957

Thanks for your kind explanation.

Yes, I understand what you're saying.
And I should change the transport properties of two phases according to gamma-definition.

Then,
It'll be a good idea to modify all transportProperties in cavitatingFoam-tutorials.

best regards
Scurry

henry

2013-03-06 09:52

manager   ~0001958

What is wrong with the transportProperties in the cavitatingFoam tutorials?

wyldckat

2015-01-27 22:30

updater   ~0003599

After trying to look at this bug report from a few of several possible perspectives, most of them assuming there was a communication/report issue, I have deduced that this issue has already been resolved at least since OpenFOAM 2.3.0 was released.

My best hypothesis is that the confusion is revealed by the following commands:

    ~/OpenFOAM/OpenFOAM-2.1.x/tutorials/multiphase/cavitatingFoam$ grep -r gamma *
    les/throttle/system/controlDict: gamma
    les/throttle/0/p: gamma 1;
    les/throttle/0/gamma: object gamma;
    les/throttle3D/system/controlDict: gamma
    les/throttle3D/0/p: gamma 1;
    les/throttle3D/0/gamma: object gamma;
    les/throttle3D/0.org/p: gamma 1;
    les/throttle3D/0.org/gamma: object gamma;
    ras/throttle/0/p: gamma 1;
    ras/throttle/0/gamma: object gamma;

Versus:

    ~/OpenFOAM/OpenFOAM-2.3.x/tutorials/multiphase/cavitatingFoam$ grep -r gamma *
    les/throttle/0/p: gamma 1;
    les/throttle3D/0.org/p: gamma 1;
    ras/throttle/0/p: gamma 1;


Therefore, there is no longer ambiguity of gamma versus alpha.

Issue History

Date Modified Username Field Change
2013-03-05 02:46 user584 New Issue
2013-03-05 16:53 henry Note Added: 0001956
2013-03-06 09:24 user584 Note Added: 0001957
2013-03-06 09:52 henry Note Added: 0001958
2015-01-27 22:30 wyldckat Note Added: 0003599
2015-01-27 23:29 henry Status new => closed
2015-01-27 23:29 henry Assigned To => henry
2015-01-27 23:29 henry Resolution open => no change required