LARGE-SCALE HAIRPIN VORTICES FROM A PAIR OF SURFACE-MOUNTED HEMISPHERES AT A LOW REYNOLDS NUMBER

摘要

Flow visualization experiments are conducted to study the hairpin vortices which are shed from the wakes of a pair of surface-mounted hemispheres at a Reynolds number of about 500. The results show that the number of groups of the hairpin vortices can be one, two or three, depending on the gap between the hemispheres. As the gap increases from zero, the number of groups varies from one to three first. Then it reduces to two when the gap is large enough for the individual wakes to prevail.