Title: How tracer particles sample the complexity of turbulence,
Abstract: On their roller coaster ride through turbulence, tracer particles sample the
fluctuations of the underlying fields in space and time. Quantitatively
relating particle and field statistics remains a fundamental challenge in a
large variety of turbulent flows. We quantify how tracer particles sample
turbulence by expressing their temporal velocity fluctuations in terms of an
effective probabilistic sampling of spatial velocity field fluctuations. To
corroborate our theory, we investigate an extensive suite of direct numerical
simulations of hydrodynamic turbulence covering a Taylor-scale Reynolds number
range from 150 to 430. Our approach allows the assessment of particle
statistics from the knowledge of flow field statistics only, therefore opening
avenues to a new generation of models for transport in complex flows.