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-   -   the level of LES now? (http://www.cfd-online.com/Forums/main/128429-level-les-now.html)

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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