This transition mechanism occurs in cases where the laminar boundary layer separates and transition takes place inside the bubble. The size of the bubble depends on many factors, like the Re number, the pressure gradient and the turbulence intensity.

The current formulation enhances the intermittency to higher values than =1 in the bubble regime, as it was observed that otherwise the turbulence models might not react quickly enough to close the bubble under low conditions.

(4–214)

(4–215)

(4–216)

(4–217)

where

(4–218)

(4–219)