Joint statistics of acceleration and vorticity in fully developed turbulence

We report results from a high-resolution numerical study of fluid particles transported by a fully developed turbulent flow at R _λ = 280. Single-particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov timescale up to one large-eddy turnover time. We present results concerning acceleration statistics and the statistics of trapping by vortex filaments conditioned to the local values of vorticity and enstrophy. We found that a suitable observable, a _⊥ = a × v, connected to the centripetal acceleration, is strongly sensitive to the trapping of particles into vortex filaments. In particular, we found that its sign may persist up to 10–15 τ_η, while the typical oscillation of the longitudinal acceleration happens on a time lag of a few τ_η.

Acknowledgements

We thank G. Boffetta, A. Celani, B. Devenish, and A. Lanotte for discussions. We thank the supercomputing center CINECA (Bologna, Italy) and ‘Centro Ricerche e Studi Enrico Fermi’ for the resources allocated for this project. We acknowledge Dr Nazario Tantalo for technical assistance.