Three-dimensional visualization technique, "coloured slit method", have revealed some coherent phnomena of turbulence in a pipe. High-speed inflow and streamwise vortex were observed as strucures related to the ejection, and their properties were made clear through the quantitative mesurements of instantaneous Lagrangian velocity profiles and Reynolds stress by the data of visualization after some laborious procedures.

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The laminar horseshoe vortex system formed around the permeable-wall cube by a separating boundary layer has been investigated using a water tunnel experimentally. Visualization of the flow fields around the cube with four open area ratios has been made by use of the dye method. The various aspects of horseshoe vortex systems which are visible upstream of the permeable-wall cube are described in connection with the value of open area ratio and the flow direction. The results show that the open area ratio and the flow direction largely affect the steady horseshoe vortex system. According, to the present results, the scale of the primary vortex becomes small and it's location approaches the cube with the open area ratio increasing. In the case of α=45 deg., the location, of various vortices approaches the cube compared with the case of α=0 deg.

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