  We study the motion of passive tracers in a two-dimensional turbulent
velocity field generated by the Kuramoto-Sivashinsky equation. By varying the
direction of the velocity-vector with respect to the field-gradient we can
continuously vary the two Lyapunov exponents for the particle motion and
thereby find a regime in which the particle distribution is a strange
attractor. We compare the Lyapunov dimension to the information dimension of
actual particle distributions and show that there is good agreement with the
Kaplan-Yorke conjecture. Similar phenomena have been observed experimentally.
