Abstract
A flow field produced by a vortex pair travelling across a thin circular cylinder was investigated using both a smoke visualization technique experimentally and a 2-D vortex method numerically. The thin circular cylinder was set parallel to a vortex tube in a core of a vortex pair. Particular attention was paid to the case of a vortex core colliding with and travelling across the cylinder. The disturbance to the vortex core, made by the direct collision with the cylinder, was unexpectedly so small that the vortex pair traveled without changing its original direction of motion even after the interaction. This unexpected feature could be qualitatively explained by two combined effects, i. e., the anticoncentration of vorticity while a vortex core was travelling across the cylinder and the conservation of effective circulation in the disturbed core of vortex pair according to the numerical simulation of the vortex method.
