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Old   August 21, 2010, 07:40
Question Time Step in LES
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Saeed Salehi
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Hi Every one.
i want to solve a turbulent model in fluent with LES. as you know LES is a transient model. my problem is that i dont know how much my time step should be.
is there any body help me?
tnx.
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Old   August 23, 2010, 04:51
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Dong Liang
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hi,
generally speaking, the time step in les is the reciprocal of Re number.
i.e. if the Re number is 2000, the time step should be no more than 0.0005.
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Old   August 23, 2010, 05:47
Default Time step is LES for Re=10^5
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Saeed Salehi
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Thank you. dear davedong.
wow what a small time step! my problem Re is 10^5. do you know how much my time step should be? or generelly is there any releation between Re and best time step?

Best Regards.
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Old   August 23, 2010, 22:45
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Dong Liang
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Quote:
Originally Posted by salehi144 View Post
Thank you. dear davedong.
wow what a small time step! my problem Re is 10^5. do you know how much my time step should be? or generelly is there any releation between Re and best time step?

Best Regards.
hi,
as i know, it's a rule in Smagorisky model. the reciprocal of Re is equal to the small spacial scale divided by the velocity, in another word, the time step size.
10e-5 time step size is OK. it is absolutely right.
my native language is not english. may it will not make you misunderstand.

Last edited by davedong; August 24, 2010 at 02:16.
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