Computation of separated-flow transition using a two-layer model of turbulence

A two layer model of turbulence is employed to predict transition in flows, along with a suitably defined intermittency function, which takes appropriate values in the laminar, transitional, and turbulent flow regions. Correlations derived from measurements are used for this purpose. Two test cases were selected: the flow over a long horizontal body with semicircular leading edge and the flow over the backward facing step of small height. The Reynolds number, based on the diameter in the first case and on the step height in the second, lie in the range of 1600-6600, in which limited numerical investigations were previously available and where bubbles with laminar separation and turbulent reattachment are expected.