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 yzeyue January 12, 2014 05:12

the level of LES now?

hello,

i am new in les. My teacher ask me what is the level of LES now, what Renolds?
and can it use in complex boundary conditions now？

thank u very much！

 cfdivan January 13, 2014 16:21

Hi yzeyue,

Your question is quite vague. There are plenty of books regarding turbulence modelling that may help you.

LES is essentially a simulation that directly solves the large scale motion but approximates the small scale. Through the LES model u can resolve all large turbulent strucutres up to the available grid limit. The small structures are modelled, by imposing a filter method, SGS. There are plenty of subgrig scale models.

BTW, LES simulation are usually quite expensive. U can find:
Purely LES models (quite expensive within BL)
Hybrid ones (RANS within BL) and LES outside of it which reduce a lot the computation costs (very often referred as Wall modelled LES).

As u can see, it can be quite interesting this turbulence model :) which became one of the most appellative with the advent of high performance computers!

What u mean by saying complex boundaries? AFAIK u can deal with any type of BC's as in RANS!

Regards

 yzeyue January 15, 2014 05:41

Quote:
 Originally Posted by cfdivan (Post 469864) Hi yzeyue, Your question is quite vague. There are plenty of books regarding turbulence modelling that may help you. LES is essentially a simulation that directly solves the large scale motion but approximates the small scale. Through the LES model u can resolve all large turbulent strucutres up to the available grid limit. The small structures are modelled, by imposing a filter method, SGS. There are plenty of subgrig scale models. BTW, LES simulation are usually quite expensive. U can find: Purely LES models (quite expensive within BL) Hybrid ones (RANS within BL) and LES outside of it which reduce a lot the computation costs (very often referred as Wall modelled LES). As u can see, it can be quite interesting this turbulence model :) which became one of the most appellative with the advent of high performance computers! What u mean by saying complex boundaries? AFAIK u can deal with any type of BC's as in RANS! Regards
Thx very much!

I majored in axile compressor, and my teacher hope that I can learn and use LES in the compressor's optimization.

I do not know how high is the Reynold can be done now.

Thx!

 FMDenaro January 15, 2014 05:45

for LES of compressible flows, you can find some help in the book of Sagaut
http://www.springer.com/physics/theo...-90-481-2818-1

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