FLOW VISUALIZATION OF HORSESHOE VORTEX FORMED AROUND COLUMNS PLACED VERTICALLY TO A FLAT PLATE AT VARIOUS SPACING

The flow around a circular cylinder or a rectangular column placed at various spacing to a flat plate has been investigated experimentally by making use of visualization technique. An open channel is used for the experiment, and the column is placed vertically to the bed. The method of flow visualization used in this report is the beam sweep laser speckle photography. The plane of observation is illuminated by periodical sweeps of a laser beam scanned by a galvanometer mirror, and multi-exposure photographs of speckle pattern of the flow seeded with tracer particles are recorded. Visualization results clearly show the change of horseshoe vortex system with the spacing between the end face of column and the bed of the channel.