Experimental study was performed to investigate X-shaped intersecting flows in multiple diamond-shaped islands. Two kinds of upstream and downstream apex angles in islands were 30° and 60°. Flow control was performed by placing a turbulence mesh at a right side in the front surface of the first-row of diamond-shaped islands. The X-shaped flows in intersecting regions were visualized using the fluorescein dye illuminated by a laser light sheet. The velocity variations in their flow fields were measured using two-dimensional laser Doppler velocimetry (LDV). It is found that the difference of flow patterns depends on the arrangement of the diamond-shaped islands, the Reynolds number, the existence of the turbulence mesh, and row numbers of diamond-shaped islands. The characteristics of velocity variations in the X-shaped intersecting flows are also clarified in each intersecting region of diamond-shaped islands.

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The turbulence flow around a square or diamond-shaped cylinder has received far less attention than the flow around a circular cylinder. An experimental study was performed to visualize the wake flows behind a diamond-shaped cylinder. Several kinds of aspect ratios d/w and b/w were selected in the experiment, where w was a width of the cylinder, d and b were a depth and width of the duct, respectively. The wake flows were visualized at a top view, a side view and rear views using the fluorescein dye illuminated by a laser light sheet. The velocity variations in the flow field were measured using two-dimensional laser Doppler velocimetry. It is shown that the three dimensional longitudinal vortices appear in the wake flows behind the diamond-shaped cylinder. The characteristics of the turbulence in the wake flows behind it are clarified.

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