The shielding function developed within the SDES framework can be extended to achieve a blending on the stress level between RANS and LES formulations. In general terms, this affects the turbulence stress tensor in the following way:
 | (4–296) |
where 
is the RANS portion and 
is the LES portion of the modeled stress tensor. In cases where both models are
based on eddy viscosity concepts, the formulation simplifies to:
 | (4–297) |
Such a formulation is only feasible due to the strength of the shielding properties of the
shielding function 
(as described in the previous section).
The main advantage of the SBES model is that it allows you to use a given LES model in the LES portion of the flow, instead of relying on the LES capability of DES-like models. You can also use it to visualize the regions where RANS and LES models are used, in order to check the consistency of your setup. Finally, the SBES model allows you to have a rapid “transition” from RANS to LES in separating shear layers.
In summary, the SBES model allows you to:
generically combine RANS and LES model formulations
clearly distinguish between the RANS and the LES regions based on the
functionutilize a rapid “transition” from RANS to LES in separating shear layers, due to the low stress levels enforced by the LES model