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# les-ras
  • l
    then this is the size of your eddie when it's anisotropic
  • l
    or something like that
  • l
    idk
  • l
    but it doesn't answer the question
  • l
    everyone just says "it's the hypothesis"
  • t
    Isnt it that way because they use the same way to solve the strain strate like they do in technical mechanic?
  • l
    solid mechanic?
  • t
    yes
  • t
    I have something like this in my head but im not sure xD
  • l
    idk
  • l
    my tutor here is a solid mechanics guy. And I was expalining what I got from LES, then he asked me but why is it isotropic as small scales
  • l
    and ye still can't answer
  • t
    Kolmogorov argued that the directional biases of the large scales are lost in the chaotic scale-reduction process as energy is transferred to successively smaller eddies.
  • l
    yes
  • t
    so its just a hypothesis as you said 😄
  • l
  • l
    feels like they just said "yeye turbulence is chaotic and 3D, so it must be isotropic when eddies are small enough"
  • t
    I think they did xD
  • l
    eveyone: seems good, let's spend decades building models around this
  • t
    its not that it doesnt work .D
  • t
    😄
  • l
    it's like the principles of thermo
  • l
    no one unconfirmed this yet
  • l
    so there it is
  • t
    yeah maybe the find entropy2 in some years 😄
  • t
    and then they have to do second law of thermodynamic again 😄
  • t
    Well, it is all just models that are close enough (sometimes just because other effects are giant in comparison)
  • t
    My Professor once said: Of cause it is wrong, just go and write down the correct way and we will soon all adopt this.
  • t
    We basically just did what is written here: https://en.wikipedia.org/wiki/Taylor_microscale to approximate eddies... not for real cases though, was just in the exam.. i only used RANS and laminar so far
  • l
    (y)
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