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Old   March 19, 2010, 10:51
Default Bounding epsilon or bounding omega
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Stylianos Kyriacou
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Hello Everyone

I'm trying to run an axial turbine simulation via MRFSimpleFoam (Rotor-Stator with GGI interface), i've tried both kEpsilon and kOmegaSST turb-models but i get either bounding omega (in case of the kOmega) or bounding epsilon (in case of kEpsilon) with negative values dose anyone have any idea about that?

i use:
inlet:
U
: flowRateInletVelocity
p: zeroGradient
k: turbulentIntensityKineticEnergyInlet
epsilon: turbulentMixingLengthDissipationRateInlet
omega: turbulentMixingLengthFrequencyInlet

outlet:
U: inletOutlet
p: fixedMeanValue
k/epsilon/omega: inletOutlet

with turbulentIntensity = 5%
and MixingLength = 0.079 (1/5*(smaller diameter of my duct))

Stelios
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Old   March 23, 2010, 07:21
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Stylianos Kyriacou
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Managed to get kOmegaSST running,
Had to initialize omega field with omega = epsilon/(Cm*k) and not epsilon/k as mentioned in several threads.

no luck with kEpsilon thought.

Hope this is useful for someone,
Stelios
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Old   November 3, 2010, 06:21
Default the same problem
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Mohammad.R.Shetab
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Dear Stelios
I have the same problem with my case that is a centrifugal fan with a duct, my boundary condition is almost similar to you. First, my model would diverge at about 10 iterations.(k and epsilon would blow up). I changed my fvSchemes and fvSolutions dictionaries and got better answers. At least with no divergence until about 200 iterations, but after that it would diverge again.

Could you solve your problem?
It you could, tell me what you did.

Good luck
Mohamadreza
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Old   November 4, 2010, 05:49
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Stylianos Kyriacou
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Hello Mohamad

The only think i managed to do to get a solution was to use kOmegaSST turbulence model instead of kEpsilon. But that was some time ago and with OF 1.5-dev i don't know if there is something else going on in 1.6.

Stelios
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Old   November 10, 2010, 02:03
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Hi Stelios,

I am using kOmegaSST turbulence model in rhoPisoFoam. I am getting bounding omega with negative values. I have also given initial value of omega, still bounding omega is appearing. My case is not crashing but it's also not showing the right flow profile. I'm guessing the problem lies with the bounding omega. Is there any suggestion that bounding omega can be eliminated by changing any of the parameters? Thanks!

Novi
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Old   June 9, 2011, 00:40
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farahidayu
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Hi Kaka,
Have you solved the problem?
I am also facing similar problem as yours..

Ayu
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