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time steps in LES

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Old   October 14, 2002, 09:41
Default time steps in LES
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Jimmy
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could someone give me a good method to set a correct time step in LES simulations. The only infos given by the manual says : "under 20 iteration to converge"

i'm not sure this is a good argument to put in a scientific work

I've tried using a CFL condition witch could be interpreted as : "the information cannot jump to the next cell during one time step" but the CFL conditions given in the manual refers to the coupled solver and i use the segregated one.

any idea ?
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Old   October 14, 2002, 10:07
Default Re: time steps in LES
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fb
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You can just consider the max. streamwise velocity and the smallest cell size in the same direction to evaluate a time step (this will be cfl~1).

For exemple channel flow with streamwise x direction with vmoy ~1 and DeltaX =0.01 => Delta t= 0.01 ....
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Old   October 14, 2002, 10:44
Default Re: time steps in LES
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Jimmy
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that's what i'm actually using, while adapted after some readings to CFL=0.3

but this is true only for stability in explicit time integration, is there a good justification for this in an implicit second order time integration ?
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