  Three types of streamline topology in a Karman vortex street flow are shown
under the variation of spatial parameters. For the motion of dilute particles
in the K\'arm\'an vortex street flow, there exist a route of bifurcation to a
chaotic orbit and more attractors in a bifurcation diagram for the proportion
of particle density to fluid density. Along with the increase of spatial
parameters in the flow filed, the bifurcation process is suspended, as well as
more and more attractors emerge. In the motion of dilute particles, a drag term
and gravity term dominate and result in the bifurcation phenomenon.
