Hi Friends

These days I'm studing the Large Eddy simulations for Turbulence. Why we want to introduce the filtered velocity for LES? and why we filtered Navier-Stokes equation for the LES?

Thank you

Ranga

In LES, you must need to use a filter (there are some different types of filters in literature) to seperate large eddies which you will simulate directly from the small eddies which you will model.

Just think a filter is like a net, using this you will catch big fishes (wavenumber < cut off wavenumber) and drop small fishes (wavenumber > cut off wavenumber).

Hope this helps.

Manosh