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Normalization of the energy spectrum and homogeneous turbulence |
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March 15, 2019, 04:40 |
Normalization of the energy spectrum and homogeneous turbulence
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#1 |
Senior Member
luca mirtanini
Join Date: Apr 2018
Posts: 165
Rep Power: 8 |
Hi,
I have two doubts: 1. I have not understood the scope of the Energy spectrum normalization. The only explanation that I found can be the comparison between more graph in order to align them in the inertial subrange, as done here at page 350 http://storm.colorado.edu/~jweiss/50...avalli1994.pdf 2. Someone can explain me the definition of homogeneous turbulence? I cannot understand why a turbulence can be defined homogeneous since, turbulence is always confined in an area as a wake or a jet. Thank you |
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March 15, 2019, 06:03 |
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#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,768
Rep Power: 71 |
Quote:
1. Consider that making a variable non-dimensional is simple but does not guarantee that the non-dimensional values are of O(1). Normalization means you use the proper reference variables to get that, 2. there is a standard definition in terms of the property of the statistics, just see a statement on Wikipedia https://en.wikipedia.org/wiki/Homoge...pic_turbulence |
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March 15, 2019, 08:19 |
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#3 |
Senior Member
luca mirtanini
Join Date: Apr 2018
Posts: 165
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1. I have asked why they decided to normalise
2. I ve already seen this wikipedia page. My question was: how can this theory work for turbulence which is confined only in particular area. |
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March 15, 2019, 08:40 |
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#4 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,768
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So you have the answer: if the statistics depend on the translated location, the flow is not homogeneous. This is what happens, for example, when you move along the normal direction to a wall.
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March 15, 2019, 10:18 |
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#5 |
Senior Member
luca mirtanini
Join Date: Apr 2018
Posts: 165
Rep Power: 8 |
When a flow can be approximated as homogeneous?
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March 15, 2019, 10:58 |
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#6 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,768
Rep Power: 71 |
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