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-   -   Problem calculate Y in compressible turbulence model (http://www.cfd-online.com/Forums/openfoam-solving/60188-problem-calculate-y-compressible-turbulence-model.html)

luca May 31, 2006 11:00

Hi all, May be It's a studp
 
Hi all,

May be It's a studpid question but I've noticed in file "turbulence.C" in compressible turbulence models that OF calucalte Y+ like:

Yp = pow(Cmu.value(), 0.25)
*y_[patchNo]
*sqrt(k()().boundaryField()[patchNo].patchInternalField())
/(
mu().boundaryField()[patchNo].patchInternalField()
*rho_.boundaryField()[patchNo]<---
);

I think that it's wrong because I need the Kinematic viscosity that is defined as


mu/rho. (I think that mu is refereed to Dynamic viscosity)

and so the right way to calculate Y+ is

Yp = pow(Cmu.value(), 0.25)
*y_[patchNo]
*sqrt(k()().boundaryField()[patchNo].patchInternalField())
/(
mu().boundaryField()[patchNo].patchInternalField()
/rho_.boundaryField()[patchNo]<---
);



I'm wrong ?!

Luca

pierre May 31, 2006 11:41

Hi, In the calculation of Y
 
Hi,

In the calculation of Yplus in wallViscosity.H and WallFunctions.H for compressible flow codes, it is written:
"
scalar yPlus =
Cmu25*turbulenceModel::y_[patchi][facei]*sqrt(k_[faceCelli])
/(muw[facei]/rhow[facei]);
"
which is as you suggest, so I guess you might be right. Thought that member function defined in turbulence.C is not used anywhere it seems.

Pierre

luca May 31, 2006 11:58

Hi Pierre, So It's a bug..
 
Hi Pierre,

So It's a bug..

I use the function Yp in turbulence.C to check y+ for compressible turbulence model that I use. In detail I build the utility starting from "checkYPlus" incompressible utility where, I think, it uses Yp function.

So how do you suggest me to build my utility to check y+ without Yp function in turbulence compressible model?!

Thanks in advance

Luca

pierre May 31, 2006 12:19

why don't you calculate Yplus
 
why don't you calculate Yplus directly as you wrote it above without using Yp function?

Pierre

mattijs June 1, 2006 05:16

Thanks Luca, it was a bug and
 
Thanks Luca, it was a bug and has been fixed. Any more of these? If so please report them on the bugs list so we can keep track.

luca June 1, 2006 05:53

Ok,Mattijs!! Thanks for the
 
Ok,Mattijs!!

Thanks for the suggestion, and support.

Luca


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