Hello everyone
I want to depict eddies and vortex and find the max diameter of them with mean velocity in tecplot, question is that how should I consider mean velocity and how determine the max diameter and how depict them in tecplot?
thanks for your answers in advance.
The information about turbulent length scales is not contained in just this single physical and averaged quantity, i.e. mean velocity. You need at least additional information about turbulent kinetic energy and dissipation rate (or turbulent frequency omega). In this case you can determine a local characteristic turbulent length scale and plot it as e.g. contours of a field property. But it is NOT the "max diameter of eddies". It is a measure to characterize the manifold of bypassing eddies at a certain space location in terms of Reynolds averaged N.-S. equations.
What is the underlying simulation (or measurement) and which data are available besides only the mean flow velocity?
Regards,
Dr. Th. Frank.
Thanks for your answer Thomas Frank
I have fluent results but I should use mean velocity for calculating Q-criterion, and I don't know how should I consider mean velocity in tecplot because tecplot calculate Q by itself.
furthermore how can I measure size of these eddies in tecplot or fluent?
Mahtab Alipour : If you have Fluent, than you have CFX5Post (alias CFD-Post). CFX5Post is calculating Q by itself as well. Just visualize vortex cores and specify a value for the level of Q to be visualized. Since the size of these visualized eddies depends on the level of Q, it does not make sense to measure them in absolute measures. It is just a visualization technique for vortex systems in flows in order to get a better idea of the flow structure itself.
Regards,
Dr. Th. Frank.
The eddies size can be calculated by using corresponding to the Lagrangian integral time scales tL for macro turbulence eddies by applying the Taylor’s frozen flow field hypothesis.
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