Visualization of a mechanism for three-dimensional interaction and near-wall eruption

Abstract

An experimental configuration has been found which allows detailed observation of three-dimensional vortex–vortex and associated vortex–surface interactions which appear similar to those observed in fully turbulent flow. Hydrogen bubble visualization illustrates a complicated intertwining, or braiding, of two initially co-rotating vortices. It is observed that the three-dimensional interactions of the braided vortices induces a pair of local surface-fluid eruptions reminiscent of the ‘bursting’ behaviour characteristic of the near-wall regeneration process of fully turbulent boundary layers.