19 壁面乱流の壁近傍領域における流れ方向渦度の測定

抄録

Coherent fluid motions near the wall in a two-dimensional turbulent channel flow have been visualized by using a sophisticated hydrogen-bubble technique with partially insulated fine tungsten wires, which generate segmental hydrogen-bubbles, at several distances from the wall. The motions of the segments of bubbles are illuminated in the thin frame perpendicular to the flow direction and are recorded in 16mm motion pictures. These flow visualizations supply not only a direct evidence for the existence of streamwise pseudo-vortical motions but quantitative data of fluid motions in the wall region. Further data reduction with a micro-computer produces instantaneous distributions of two velocity components of v and w as well as streamwise vorticity of w _x in the y-z plane, which are extremely difficult to obtain by conventional probe measurements.