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-   -   LRN turbulence models in Fluent (https://www.cfd-online.com/Forums/fluent/28067-lrn-turbulence-models-fluent.html)

Luo Shengping December 4, 2000 08:19

LRN turbulence models in Fluent
 
Hello,

Is there anyone who knows how the LRN(low-Reynolds number) turbulence models were implemented in Fluent? How can we check the grids in the near wall region: like with the two-layer zonal model to check y+ =1 or....? Thank you for your feekback!

Cheers,

Shengping LUO

dory December 5, 2000 11:07

Re: LRN turbulence models in Fluent
 
PARA IMPLEMENTAR ESTE MODELODEBES EN PANTALLA ESCRIBIR LO SIGUIENTE: DEFINE/MODELS/VISCOUS/LOW-RE-KE

LUEGO, LA TECLA 'ENTER' Y PODRAS COLOCAR EL MODELO DE BAJO REYNOLDS QUE DESEES, FLUENT POSEE CERCA DE 5 MODELOS DISTINTOS, IR A ESTA PAGINA PARA CONOCERLOS:

HTTP://WWW.CAEWISC.EDU/MANUALS/FLUENT5.2/FLUENT5

Luo Shengping December 6, 2000 03:56

Re: LRN turbulence models in Fluent
 
Hi,

Thank you for your reply, but I cannot understand what you write: it's in which language? On the other hand, I can't visit the site you gave me: I was told the site "does not have a DNS entry". Could you check if there is an error in the address of the site? Much thanx!

Shengping

dory December 6, 2000 07:55

Re: LRN turbulence models in Fluent
 
sorry, I write in spanish, but now it will try to explain in english.

IN ORDER TO IMPLEMENT THIS MODEL YOU MUST IN SCREEN WRITE THE FOLLOWING THING: DEFINE/MODELS/VISCOUS/LOW-RE-KE SOON, KEY ' ENTER' AND PODRAS TO PLACE THE MODEL OF LOW REYNOLDS WHO YOU WISH, FLUENT HAS NEAR 5 DIFFERENT MODELS.

it will send to your direction the file to you so that it you read


Luo Shengping December 6, 2000 09:39

Re: LRN turbulence models in Fluent
 
Hi Dory,

Thank you again for your quick response: this is what I have done. My problem is: how to check the mesh dependence(or independence)? They just say that you should have very fine mesh near wall, but how fine of the mesh is enough? With two layer model they give you a criteria Y+=1 (or Y+=4~5), but with LRN, I cannot find any information for what I should check. The above method you described can just be found in the release note. Do you have any suggestions with LRN in Fluent? Thanx!

Regards,

Shengping

Frédéric Launoy December 22, 2000 10:45

Re: LRN turbulence models in Fluent
 
Hi Luo,

You're right. For the LRN, the criterium for the y+ is the same as for the 2-layer model, that is to say, theoritically you should try to have y+=1. In any case, the value should not exceed 5.

Best regards, merry Christmas and good luck (the convergence is hard to get with LRN)

Fred

Luo Shengping December 22, 2000 10:59

Re: LRN turbulence models in Fluent
 
Hi Frédéric,

Merry Christmas and Happy New Year to you too. Yesterday Dr. Kim of Fluent Co. confirmed me as you have said, but thank you for your kind reply just the same. Hope the solution will be converged:)!

Regards,

Shengping


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