In computational fluid dynamics, the k–omega (k–ω) turbulence model is a common two-equation turbulence model, that is used as an approximation for the Reynolds-averaged Navier–Stokes equations (RANS equations).
The model attempts to predict turbulence by two partial differential equations for two variables, k and ω, with the first variable being the turbulence kinetic energy (k) while the second (ω) is the specific rate of dissipation (of the turbulence kinetic energy k into internal thermal energy).
The eddy viscosity νT, as needed in the RANS equations, is given by: νT = k/ω, while the evolution of k and ω is modelled as:[1]
ρ ω k +
μ +
ω
∂ ( ρ ω )
ω )
α ω
− β ρ
ω
μ +
ω
ω
∂ ω
ω
∂ ω
{\displaystyle {\begin{aligned}&{\frac {\partial (\rho k)}{\partial t}}+{\frac {\partial (\rho u_{j}k)}{\partial x_{j}}}=\rho P-\beta ^{*}\rho \omega k+{\frac {\partial }{\partial x_{j}}}\left[\left(\mu +\sigma _{k}{\frac {\rho k}{\omega }}\right){\frac {\partial k}{\partial x_{j}}}\right],\qquad {\text{with }}P=\tau _{ij}{\frac {\partial u_{i}}{\partial x_{j}}},\\&\displaystyle {\frac {\partial (\rho \omega )}{\partial t}}+{\frac {\partial (\rho u_{j}\omega )}{\partial x_{j}}}={\frac {\alpha \omega }{k}}\rho P-\beta \rho \omega ^{2}+{\frac {\partial }{\partial x_{j}}}\left[\left(\mu +\sigma _{\omega }{\frac {\rho k}{\omega }}\right){\frac {\partial \omega }{\partial x_{j}}}\right]+{\frac {\rho \sigma _{d}}{\omega }}{\frac {\partial k}{\partial x_{j}}}{\frac {\partial \omega }{\partial x_{j}}}.\end{aligned}}}
For recommendations for the values of the different parameters, see Wilcox (2008).