The Realizable k-
ε turbulence model (
Ref. 14) is an extension to the standard
k-
ε model with built-in realizability conditions,
The turbulent viscosity is given by Equation 3-76, but
Cμ is not constant for the realizable
k-
ε model,
Sij and
Ωij are the mean strain- and rotation-rate tensors respectively. The default constants for the Realizable
k-
ε model are,
Compared to the standard k-
ε model, the realizable
k-
ε model yields better predictions for certain flows. One example is the round jet, for which the standard
k-
ε model overestimates the spreading rate. In general, since the realizability conditions in
Equation 3-87 are approached asymptotically, the turbulence characteristics are more consistent than for the standard
k-
ε model. The realizable
k-
ε model uses wall functions and has the same default initial conditions and scalings as the standard
k-
ε model (see
Wall Functions,
Initial Values and
Scaling for Time-Dependent Simulations).