Laminar to turbulent transition occurs in a broad range of industrial applications, and in nature. There are many mechanisms (natural or bypass) that lead to transition. Accurately predicting both the onset location and length of transition has been persistently difficult. A new, local, intermittency-function-based transition model for both low (< 1%) and high freestream turbulence intensity flows, over smooth and rough surfaces, is introduced and formulated. It is coupled with the k-ω RANS model.

The intermittency model was validated on the ERCOFTAC experimental zero-pressure-gradient smooth flat plate boundary layer cases T3A-, T3A, T3B with leading-edge freestream turbulence intensity 0.9%, 3.5%, 6%, respectively. Skin friction profiles agree well with the experimental data. The model was then tested on periodic wakes, and flows over Stripf’s turbine blades with a broad range of roughnesses, from hydraulically smooth to fully rough. The predicted skin friction and heat transfer properties by the current model agree well with the published experimental and numerical data.

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