[Lance]

Hi,
I've read a couple of papers where people have computed the eddy-viscosity ratio and used it to motivate the use of LES in their low-Re models. For example, if the eddy-viscosity ratio becomes 0.30, some authors claim that the subgrid scale dissipates 30% of the energy of the flow, which justifies their use of LES compared to a laminar solution.

Is this really true? And what happens when the eddy viscosity ratio becomes more than 1? Does that mean that the subgrid scale dissipate more energy than there is in the flow?

edit: on second thought, energy is also created in the subgrid scale. Is that why the ratio can become more than 1?