Abstract
A flow produced by a vortex pair approaching a circular cylinder was numerically analyzed by using the discrete vortex methods due to the Cheer's model and due to the modified ones proposed in this paper.
The two major features of the flowfield obtained by the previous experiment are the generation of the secondary vortices of large scales and the characteristic motions of the vortex pair widening largely their mutual distance. These features were found to be well simulated by the vortex methods. Moreover, the tertiary vortices were predicted to arise by the present simulation, which were confirmed to appear by the smoke visualization.
Further, we discussed regarding adequate time intervals of the generation of successive discrete vortices on the solid surface, which is a problem arising from the discrete vortex method itself. Also, a modified “Cloud In Cell” method was proposed for the better expression of the vorticity field to transform the discrete vortex field to a continuous field.
