see last two answers :

i'm lazy to try to understand properly now, but tomorrow I will 😄

o boi

look at this

The Quote that was mentioned I had to learn as well: "Big whirls have little whirls that feed on their velocity, and little whirls have lesser whirls and so on to viscosity."

paper from last month

way too many equations for me

it says that the true cause of the energy cascade is not vortex stretching (it is, partially), but mainly strain self-amplification (what is that even)

mmh this is a good question 😄

sounds like the eddys are killing them self by hitting them selfs stronger ^^

this paper is tough

It has not been peer rewieved, right?

yeah they had a lot of bug fixing but still you could give it a try ^^ depence on what your goal is you could compare the result than say its bullshit or not 😉

Hi, if you ever try LES, you might encounter stuff like this :

this wavy garbage is due to central difference + mesh grading

the actual reason is for these is "pressure-velocity decoupling"

so, to solve this while keeping a second order accurate scheme, there's the filteredLinear scheme

more info here : https://www.cfd-online.com/Forums/openfoam-solving/59321-convection-discretization-schemes-les.html The best available low dissipation second order schemes in OpenFOAM are filteredLinear and filteredLinear2. The filtering removes staggering caused by pressure-velocity decoupling by introducing small amounts of upwind. The type of mesh they are used on is not relevant, although the calculations will obviously be more accurate on hexes and less accurate on the same number of tets.

someone asked for reference of the schemes, look at this answer hahah :

it reduces the problem, does not delete it

update, it's now some weekend project so I go at snail pace 😄

- URANS fails to capture high frequency vortex shedding, what is the reason for this? I was said it's in it's definition : when deriving URANS you take your velocity field u and decompose it into mean + fluctuation part so that u = u_mean + u'. Nice. For the convection term, at some point you have u*u, so :

(u_mean + u') * (u_mean + u') * = u_mean*u_mean + 2*u_mean*u' + u'*u' The assumption here is that the turbulent scaled is veri smol, so that when averaging that, avg(u') = 0, so avg(2*u_mean*u') = 0 also. This is a reason why by taking delta_t --> 0 for URANS solution, you will never converge to DNS results