Dispersion of tracer particles in a compressible flowJ. R. Cressman1, W. I. Goldburg1 and J. Schumacher2
1 Department of Physics and Astronomy, University of Pittsburgh Pittsburgh, PA 15260, USA
2 Fachbereich Physik, Philipps-Universität - D-35032 Marburg, Germany
(Received 12 November 2003; accepted in final form 5 February 2004)
The turbulent diffusion of Lagrangian tracer particles has been studied in a flow on the surface of a large tank of water and in computer simulations. The effect of flow compressibility is captured in images of particle fields. The velocity field of floating particles has a divergence, whose probability density function shows exponential tails. Also studied is the motion of pairs and triplets of particles. The mean-square separation is fitted to the scaling form , and in contrast with the Richardson-Kolmogorov prediction, an extended range with a reduced scaling exponent of is found. Clustering is also manifest in strongly deformed triangles spanned within triplets of tracers.
47.27.Gs - Isotropic turbulence; homogeneous turbulence.
47.27.Qb - Turbulent diffusion.
06.30.Gv - Velocity, acceleration, and rotation.
© EDP Sciences 2004