  We study numerically and analytically the dynamics of particles on the Galton
board, a regular lattice of disc scatters, in the presence of a constant
external force and friction. It is shown that under certain conditions friction
leads to the appearance of a strange chaotic attractor in an initially
conservative Hamiltonian system. In this regime the particle flow becomes
turbulent and its average velocity depends in nontrivial manner on friction and
other system parameters. We discuss the applications of these results to the
transport properties of suspended particles in a laminar viscous flow streaming
through scatters.
