[zagros135]

hello to everyone.

I'm new in ansys and I want to simulate an oscillating airfoil with LES and dynamic mesh. But I did not find any training in this field. Can you advise me what to do?

[Светлана]

is it for uni, for internship, or what is the context of this effort? did you do cfd before? thanks

[zagros135]

Originally Posted by Светлана

is it for uni, for internship, or what is the context of this effort? did you do cfd before? thanks

Its for university. I want to do a simulation like the below article in Reynolds less than 100 thousand.

link:https://www.sciencedirect.com/scienc...42727X19307593

yes. I did simulations 2D-steady with kwsst and k epsilon before. But I don't know about les and transient settings.

[Светлана]

Originally Posted by zagros135

Its for university. I want to do a simulation like the below article in Reynolds less than 100 thousand.

link:https://www.sciencedirect.com/scienc...42727X19307593

yes. I did simulations 2D-steady with kwsst and k epsilon before. But I don't know about les and transient settings.

Would suggest to search in literature what LES parameters and what subgrid scale model they used for this kind of a problem previously, or for similar problems with lower Reynolds numbers.


This page also has a few useful references https://www.cfd-online.com/Wiki/Larg...imulation_(LES) if you find it needs more, they can be discussed here and added to the wiki.


Please let me know if you have further questions.

[alainislas]

According to the paper, they used the dynamic Smagorinsky sub-grid scale (SGS) model. If you wanna do something similar, these are important aspects to consider from this LES work:

(1) They used a 2.9M cells hexahedral grid. Hexa mesh is a must for serious LES.
(2) Note they set the CFL condition to CFL = 0.8. Time steps are in the order of 10^(-7) sec. CFL < 1 is also a must for LES.
(3) They initialized the flow with a RANS case, and ran the LES for 2 flow through times.
(4) They imposed synthetic turbulence at the inlet
(5) They assessed the LES quality through the LES index of quality, see (Celik et al. 2006) https://doi.org/10.1115/1.3059703

I'd suggest you to first go through the LES basic theory, read about the SGS models and its significance on the TKE and energy spectrum.



In addiiton, double check if your 2D simulation is candidate for LES. From what I know LES is intrinsically 3D, just as turbulence.