4.10.3 SST $k$- $\omega$ Based DES Model

The dissipation term of the turbulent kinetic energy (see Section  4.5.1) is modified for the DES turbulence model as described in Menter's work [ 225] such that

where $F_{DES}$ is expressed as

where $C_{\rm des}$ is a calibration constant used in the DES model and has a value of 0.61, $\Delta$ is the maximum local grid spacing ( $\Delta x, \Delta y, \Delta z$).

The turbulent length scale is the parameter that defines this RANS model:

The DES-SST model also offers the option to "protect" the boundary layer from the limiter (delayed option). This is achieved with the help of the zonal formulation of the SST model. $F_{DES}$ is modified according to

with $F_{SST} = 0, F_1, F_2$, where $F_1$ and $F_2$ are the blending functions of the SST model. The default settings use $F_2$.