  Solving null-geodesic equations, behavior of angular diameter distances is
studied in inhomogeneous cosmological models, which are given by performing
N-body simulations with the CDM spectrum. The distances depend on the
separation angle of ray pairs, the mass and the radius of particles cosisting
of galaxies and dark matter balls, and cosmological model parameters. The
calculated distances are compared with the Dyer- Roeder distance, and after
many ray-shooting, the average, dispersion and distribution of the clumpiness
parameter are derived.

Astrophysics