Abstract
An application of hydrogen bubble technique and a simplified electrolytic precipitation method are proposed. These methods make it possible to visualize streaklines from unstready boundary layer near the separation point on the surface of a circular cylinder which is started impulsively in still water. The physical meaning of visualized streaklines is made clear in relation to the vorticity distribution which is estimated from the velocity field obtained by conventional hydrogen bubble technique. These methods are found useful to investigate the mechanism of convective transfer of vorticity produced on the surface of the cylinder.
