Abstract
Coloured slits method is a simple technique of three-dimensional visualization. This method has a limitation of range and somewhat rough estimation in the depth of a picture. However, it gives easily the loci of tracers in three-dimensional view, especially in a complicated flow pattern. In this paper, structure of turbulence in a pipe with squared crosssection was studied by means of this method. The pictures of flow patterns were taken with various convection speeds of camera in coincidence with local mean velocities of the flow at various position. Longitudinal vortices with nearly local mean velocities, two typical ejection patterns, that is, vortex type and abruptly ejected one, and the interaction of high speed inflow with vortices were found in the pictures among the characteristic flow patterns in the wall region.
