LES best practice: resolved and modelled turbulence kinetic energy

ari003 · April 17, 2020, 12:47

Thanks a lot for clarifying, it really helped me a lot. And last thing does that 1/2 denotes square root?

ari003 · April 17, 2020, 12:52

Thanks for the reply and it really clarified my doubt. One last thing to ask doesnt these 1/2 gets deducted from numerator and denomerator?

em17 · April 17, 2020, 13:01

You should multiply by 1/2, as the turbulent kinetic energy is given by 0.5*trace(Reynolds stress tensor).

But you are correct, in this case as we are taking the ratio of kinetic energies the 0.5 will drop out of the equation. So to find the ratio of modelled to total turbulent kinetic energy use the following equation

tr(R) / (tr(R) + tr(UPrime2Mean))

I hope this helps!

April 17, 2020, 13:01		#23
em17 New Member Emily Join Date: Nov 2017 Posts: 24 Rep Power: 8	You should multiply by 1/2, as the turbulent kinetic energy is given by 0.5*trace(Reynolds stress tensor). But you are correct, in this case as we are taking the ratio of kinetic energies the 0.5 will drop out of the equation. So to find the ratio of modelled to total turbulent kinetic energy use the following equation tr(R) / (tr(R) + tr(UPrime2Mean)) I hope this helps! ari003 likes this.

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April 17, 2020, 12:47		#21
ari003 Senior Member Arijit Saha Join Date: Feb 2019 Location: Singapore Posts: 132 Rep Power: 7	Thanks a lot for clarifying, it really helped me a lot. And last thing does that 1/2 denotes square root?

April 17, 2020, 12:52		#22
ari003 Senior Member Arijit Saha Join Date: Feb 2019 Location: Singapore Posts: 132 Rep Power: 7	Thanks for the reply and it really clarified my doubt. One last thing to ask doesnt these 1/2 gets deducted from numerator and denomerator?