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Old   October 23, 2018, 10:44
Default LES simulation
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Yuan Jiahui
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Hi everyone,


I have used k-epsilon model to calcaulate the case (in the attachment) and the result agrees well with the experiment data. Now I am trying to use LES model calculate the case again and compare the result of LES with result of k-epsilon.
Known conditions are velocity field at inlet is (0.455 0 0) and turbulent intensity is 0.04.
I choosed pisoFoam as a solver and dynamicKEqn model referring to pitzDaily in tutorials. Now I encounter severals

1. How to determine the initial value of k in 0 file? Is there any empirical fomula to get k like RANS?
2. When I choose different deltT in controlDict, the result show great difference.Why?

Any advice is welcome.
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Old   October 23, 2018, 11:54
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ssa
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Quote:
Originally Posted by yuanjiahui View Post

When I choose different deltT in controlDict, the result show great difference.Why?

Try to use pimpleFoam with adjustTimestep on and maxco 1.
This will automatically calculate the deltaT based on the courant number.
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Old   October 24, 2018, 09:04
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Michael Alletto
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Can you provide maybe some figures of the results in oder that it is easier to help?
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