Deformation of Internal Structures Caused by Interaction between Turbulent Spots

Abstract

Interaction between turbulent spots was experimentally investigated in a laminar boundary layer by using a rake of 16 I-type hotwires. Instantaneous plane views of a single spot showed that several small scale streaky structures elongated in the streamwise direction were arranged in staggered style inside the arrowhead-shaped area. The oldest streaky structures constructed the arrowhead. Newer structures were produced near the wing tip and in the interface between the turbulent and the calmed regions. When the two spots were simultaneously generated, their wing tips came to overlap each other as they grew downstream. Mutual interaction between the streaky structures at the wing tips gave birth to a strong velocity-defect region on the symmetry plane of the merged portion.