FRACTAL TRACER DISTRIBUTIONS IN TURBULENT FIELD-THEORIES

We study the motion of passive tracers in a two-dimensional turbulent velocity field generated by the Kuramoto-Sivashinsky equation. By vary ing the direction of the velocity-vector with respect to the field-gra dient we can continuously vary the two Lyapunov exponents for the part icle motion and thereby find a regime in which the particle distributi on is a strange attractor. We compare the Lyapunov dimension to the in formation dimension of actual particle distributions and show that the re is good agreement with the Kaplan-Yorke conjecture. Similar phenome na have been observed experimentally. Copyright (C) 1998 Elsevier Scie nce B.V.