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lowReynold mesh and RNGkEpsilon

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Old   March 13, 2018, 05:37
Default lowReynold mesh and RNGkEpsilon
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Thijs
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Dear Foamers,

I have a question about near wall modelling using either RNGkEpsilon or realizableKE.

I created a lowReynold mesh of a pipe with a helix structure inside (imagine a ribbed pipe) with a y+~= 1 near the pipe wall.

I tested LaunderSharmaKE which is a lowRe turbulence model. The way I understand it, this model has damping functions build inside it, such that the wall boundary conditions can be set to:

k at wall = fixedValue (0)
epsilon at wall = zeroGradient.

But I want to try a different kEpsilon model such as realizableKE and RNGkEpsilon and still use a lowReynold mesh, because my mesh quality becomes bad if I use a y+~= 30 spacing near the wall such that I can use standard wall functions.

I read about enhanced wall treatment, but I think this is a term used in FLUENT. Anyway I think RNGkEpsilon and realizableKE can be used for a lowReynold mesh but I have to activate damping functions. If I use lowRe wallfunctions am I than applying dampingfunctions to my turbulence model? I am not sure?

Bc's at the wall, would look like this:

k @ wall = kLowReWallFunction

epsilon @ wall = epsilonWallFunction

nut @ wall = nutLowReWallFunction

Thanks in advance,

Thijs
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