Some time agao i posted a question asking how to enable rng-les. i did not get any reply. anyway now i have found the way to do it, if someone needs here is the way:

1. start fluent. 2. select les model in viscous panel 3. execute this scheme command in TUI

(rpsetvar 'les-rng-sgs-on? #t)

4. read the mesh file, fluent will now prompt that rng model is now availble in interface.

[bobinson]

The command is (allow-rng-subgrid-model) type into TUI with brackets.