Fluid mechanics and heat transfer measurements in transitional boundary layers conditionally sampled on intermittency

An experimental investigation of the transition process on a flat-plate boundary layer was performed. Mean and turbulence quantities, including turbulent heat flux, were sampled according to the intermittency function. Such sampling allowed segregation of the signal into two types of behavior--laminar-like and turbulent-like. Results show that, during transition, the two forms of boundary layer behavior, identified as laminar-like and turbulent-like, cannot be thought of as separate Blasius and fully-turbulent profiles, respectively. Thus, simple transition models in which the desired quantity is assumed to be an average, weighted on intermittency, of the theoretical laminar and fully turbulent values is expected not to be successful.