A numerical procedure for predicting the receptivity of laminar boundary layers to freestream turbulence, consisting of vortex arrays with arbitrary orientation, has been developed previously. In the current paper this method is refined to improve accuracy using an unstructured computational grid. Results show that boundary layers only have high receptivity to a narrow band of normal and spanwise frequencies. The computed near wall gains have similar values to those obtained by experiment for zero pressure gradient boundary layers. Near wall gains are also obtained for a wide range of favourable and adverse pressure gradients for both attached and separated boundary layers. The gain values are used to predict start of transition values which are in reasonable agreement with Reθ values which are in reasonable agreement with the Abu-Ghannam and Shaw correlations. The current results extend transition inception prediction into the separated flow regime.

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