CFD Online Discussion Forums - Standard K-epsilon turbulence model with y~+1

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Standard K-epsilon turbulence model with y~+1

Hello,
I have a 2D mesh with

of a computational domain around a cylinder with [inlet, outlet, top, bottom, cylinder].
I want to start two simulations: using the $k-\omega$ SST and the standard $k-\varepsilon$ turbulence models without changing the mesh.

As far as I know, for the $k-\omega$ SST, the mesh is ok because y+ = 1. But for the $k-\varepsilon$ model, it requires wall functions.

Can I use a mesh that has

with the standard $k-\varepsilon$ model? if Yes which wall functions should I use at the wall (cylinder) for

(turbulent kinetic energy), and $\varepsilon$ (turbulent dissipation)?

The standard k-epsilon turbulence model cannot be used with Low-Re formulation. However you can use a Low-Re implementation, LaunderSharmaKE (it uses damping functions)

Hi Linda,
I dont know still you are looking for help regarding your Y+ and BCs.

It seems that you are clear about the wall function approach and resolving the boundary layers.

In your case, you are suppose to use Low Re k-Epsilon models.
for low Re k-Epsilon I have posted BCs long back (2013). I hope still you can use it (Please check it),

The boundary conditions are as follows (I used it for OF-2.1.1 Version),

Low Re model:

turbulence model : LaunderSharmaKE

nut ----> fixedValue (0)
k -----> fixedValue (1e-12)
epsilon -----> fixedValue (1e-8) it can be zeroGradient as well
nuTilda -----> fixedValue (0)

for high Re model:

nut ----> nutkWallFunction value (0)
k -------> kqRWallFunction value uniform (*******)
epsilon ----> epsilonWallFunction value uniform (*******)
nuTilda -----> zeroGradient

I hope it will be useful.

If there is any issue, please post it here,

Thanks,
Sivakumar