  The stickiness effect suffered by chaotic orbits diffusing in the phase space
of a dynamical system is studied in this paper. Previous works have shown that
the hyperbolic structures in the phase space play an essential role in causing
the stickiness effect. We present in this paper the relationship between the
stickiness effect and the geometric property of hyperbolic structures. Using a
two-dimensional area-preserving twist mapping as the model, we develop the
numerical algorithms for computing the positions of the hyperbolic periodic
orbits and for calculating the angle between the stable and unstable manifolds
of the hyperbolic periodic orbit. We show how the stickiness effect and the
orbital diffusion speed are related to the angle.
