On the shear stress and thermal footprints of turbulent spots at zero pressure gradient

Turbulent spots were artificially created in a flat plate boundary layer and visualized by shear-stress sensitive and temperature-sensitive liquid crystals. These procedures employ surface shear stress and temperature as passive tracers to provide insights into the structure of a turbulent spot at the near-wall region. The liquid crystals successfully displayed the "true" footprints of the spots. Quantitative data, such as the heat transfer rate, were likewise provided. The results of the present study prove the existence of a spanwise overhang on a turbulent spot, which could produce important implications on transitional modeling in gas turbine industry. © 2013 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.