As to LBM-LES with SGS and Wall function compared with LES of NS

[Yuji]

Dear all,

LBM-LES often uses the both SGS and wall function to simulate turblence .However, My understanding is that wall function often is used in RANS and I have never seen SGS+wall function in LES of NS. I think SGS with Y+ <10 grid at the wall simulates turbulence since SGS models usually are designed to consider the turbulence kinetic energy cascade. Why dose LBM uses the both SGS and wall function.

Best regards
Yuji

[stephan]

Dear Yuji,

thank you for your comment, I’ll try to answer from my personal perspective.

Apparently, it is a good thing to use wall-modeled LES (WMLES) also in direct NS solvers.
The grid requirement for doing this is much less than wall-resolved LES (i.e. LES without wall model but fine enough grid near the wall), which is why WMLES is regarded as more promising for industrial application in the near future (cf. https://doi.org/10.1063/5.0036515).

In addition, using SGS only without a wall model and without sufficiently refined grid (wrt y+), can lead to very bad results near the wall in wall-bounded turbulence.
Unfortunately, I do not have a reference for this.

BR
Stephan

• This reply was modified 4 months, 4 weeks ago by stephan.

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