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My understanding of Kolmogorov Microscale is that in a turbulent fluid, smaller eddies tend to be similiar to larger eddies - until you arrive at the microscale. My understanding (that may be wrong) is that this roughly the smallest eddy in a turbulent flow.

If I'm not wrong, then we should expect to see these 'smallest eddies' in some way. In another question by me about the subject, I was given some numbers for an estimation:

  • 100 $\mu m$ for a person running in air
  • a range for energy dissipation in ceons that translates 0,1mm to 1cm for the length scale

While small, I imagine one can design an experiment to observe flow at these scales or create a setup (less speed, more viscosity) with larger microscales. Has this been done and can I see pictures?

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mart
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2 Answers2

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The answer I believe is no, you cannot see them.

When we talk about eddy sizes, we have to understand that eddies in physical space are all superimposed and we cannot distinguish between them. All of them are stacked together, so at a given point in physical space we will see contributions from all of the eddies measuring from $l$ through $\eta$.

The other thing is that the Kolmogorov length scale is an approximate length determined by scaling laws. There are isotropic eddies smaller, there are ones larger, and there's really a continuum of eddies throughout the entire range. So you couldn't isolate that particular eddy to see it.

tpg2114
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Bare with me but I am doing a little test:

I imagine it should be this http://navier.stanford.edu/thermosciences/TSD-151.pdf figure 4.16 / 4.17 gives vortexes, and fig 4.22 / 4.23 gives how much there is dissipation.

Note There is quite a set of not so easy content to go through, before arriving to the pictures.

PS: It would help if somebody else with more insights can double check this answer.

flyredeagle
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