Multiscale Statistics of Lagrangian and Eulerian Acceleration in Turbulent Stratified Shear Flows

Direct numerical simulation data of homogeneous turbulence with shear and stratification are analyzed to study the Lagrangian and Eulerian acceleration statistics. Richardson numbers from <em>Ri</em>=0, corresponding to unstratified shear flow, to <em>Ri</em>=1, corresponding to strongly stratified shear flow, are considered. The scale...

Angular statistics of lagrangian trajectories

The angle between subsequent particle displacement increments is evaluated as a function of the timelag in isotropic turbulence. It is shown that the evolution of the average of this angle contains two well-defined power-laws, reflecting the multi-scale dynamics of high-Reynolds number turbulence.

Direction change of fluid particles in confined two-dimensional turbulence

The directional change of a fluid particle can be measured by the angle between two subsequent particle displacement increments. At small values of the time-increment the so-defined angle is proportional to the curvature of the trajectory. At large values this coarse-grained curvature should be affected by the presence of solid no-slip walls...