[TurbulenceTaxes]

Hello guys,

I am new to turbulence modeling and I have been stuck on this problem for weeks. Please help me!

So I am trying to derive the k-equation in the log layer then calculate the coefficient C for the eddy viscosity vt in the form of vt=C⋅k^1/2⋅lmix. I have read the Wilcox textbook a hundred times and tons of other papers but I still have no clue how to solve for this coefficient.

Does anyone know how the k-equation in the log layer looks like and how you solve for the coefficient for the eddy viscosity?

Best,

[sbaffini]

I haven't understood what are you looking for exactly, but two of the most relevant sources on wall functions (and log layer by consequence) are the following two:

https://citeseerx.ist.psu.edu/viewdo...=rep1&type=pdf

http://www.tfd.chalmers.se/~lada/pos..._report_WF.pdf

Have you already looked at them for an answer?

[TurbulenceTaxes]

Originally Posted by sbaffini

I haven't understood what are you looking for exactly, but two of the most relevant sources on wall functions (and log layer by consequence) are the following two:

https://citeseerx.ist.psu.edu/viewdo...=rep1&type=pdf

http://www.tfd.chalmers.se/~lada/pos..._report_WF.pdf

Have you already looked at them for an answer?

Thanks for providing these papers. Basically, there are two questions.
1:I am trying to derive the k-equation in the log-law region of a wall-bounded flow. So I used log layer assumptions. I assumed steady and fully turbulent, neglected both initial and molecular stresses, I think these are appropriate assumptions. However, I am not sure whether the turbulence kinetic energy k should be assumed to be a constant? In other two-equation models in log layer, k=ut^2/β^1/2=constant.
2: By dimensional analysis, the eddy viscosity originally has the form of Vt=Ck^1/2lmix, but in all references, they just use the constant C=1, so I am trying to figure out why C=1 or the expression for constant C.
I hope that clears my questions. Thank.

[sbaffini]

You should find an answer to both in the papers above