Nonlinear Phenomena in Complex Systems, 2002, Vol.5, No.4, pp.342-348

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

2002, Vol.5, No.4, pp.342-348

Lagrangian Particle Statistics in Turbulence.
R. Friedrich and A. Baule

We investigate the statistical behaviour of marker particles in a turbulent fluid. We formulate a hierarchy of evolution equations for N-particle probability distributions. A closure, based on the assumption of statistical independency of the Eulerian acceleration field and the Lagrangian velocities of the marker particles, lead to a closed equation for the joint position-velocity statistics of the particles. We investigate this equation for the case of a single particle and argue that the statistical behaviour of the particle velocity has to be described by a nonmarkovian process related to a continous time random walk.
Key words: turbulence, lagrangian statistics

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