Abstract
The flow around a bluff body which starts near a plane wall at low Reynolds numbers of 150 to 500 has been investigated. The drag and lift forces were measured and the corresponding flow patterns were visualized by the electrolytic precipitation method in a towing water tank, to examine the effects of and the gap-to-height ratio S/H and the width-to-height ratio B/H of a cross section of the cylinder. We find that a suction force forward to the wall is exerted on the cylinder with the B/H ratio of 0.6 and 1, and that the critical value of the gap ratio is estimated to be about 0.5; At the gap ratios S/H over 0.5, a regular vortex street can be observed and at narrower gaps than 0.5, a vortex street breaks down. There is a good correspondence between the results of measurement of lift force and flow pattern.
