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Fundamental question on the scales modelled by the k-epsilon model. |
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November 2, 2023, 15:57 |
Fundamental question on the scales modelled by the k-epsilon model.
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Mike
Join Date: Nov 2023
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Turbulent motions occur over a wide range of length and time
scales. The k-epsilon model however, models a single time and length scale at any location in the domain. The time scale is k/epsilon and the length scale is k^(3/2)/epsilon. If this time scale is very large (say 100 seconds) the length scale is also large. This modelled time scale may be interpreted as a residence time. The time it would take a particle to go around the eddy. The large value of the length scale would be interpreted as the size of this "modelled" eddy. I am trying to conclude (recall) what happens at this extreme (very large modelled eddy) condition in terms of turbulence levels. The turbulent viscosity may be shown to be proportional to the ratio of the length scale squared divided by the time scale. This would imply that the larger the time scale the lower the turbulence levels at this location. (?) Any feedback would be greatly appreciated. |
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k-e model, length scale, time scale, turbulence levels |
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