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November 21, 2013, 04:25 |
Time Step in LES
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#1 |
Member
M. Nabi
Join Date: Jun 2009
Posts: 44
Rep Power: 16 |
Hello all,
I am solving incompressible flow by LES. The model is based on Runge-Kutta-3 for the velocities. I am able to give my time step relatively large, which is almost 10 times larger than the kolmogorovtime scale for this calculation. However, in LES, as a filter is used, the time scale is larger than DNS (kolmogorov). How can we give the time step in such a way it does not exceed the physical time scale in LES. Is there any way to estimate it? Thanks |
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November 21, 2013, 04:30 |
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#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,768
Rep Power: 71 |
Quote:
In principle, the numerical stability constraint is already an useful indication for using the correct time-step. Furthermore, if LES filter you want to use is only spatial, it is suggested to use a dt that is comparable to the Kolmogorov time-scale in such a way you perform a DNS-like in time. I think that if you are no more than 10 times the Kolmogorov time-scale your dt is correct |
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