Energy flux in isotropic turbulence under large variations of external forcing

We investigate the response of energy flux in isotropic turbulence to step-function like perturbation in external forcing at large length scales. From both physical experiments and direct numerical simulations, we measured the evolution of the Eulerian velocity structure functions, such as $D_{LL}(r)$, $D_{NN}(r)$, before and after the...

Energy exchanges and time asymmetry in 3D turbulent flows

In 3D turbulent flows, the direct cascade of energy, characterized by a flux through scales, ε, is a strong source of irre- versibility. This irreversibility manifests itself in the asymmetry between negative and positive kinetic energy differences along particle trajectories. In particular, it is observed that the odd moments of the power of...

In-cloud Measurements of Drop Dynamics

We here present the results of a measurement campaign at the Umweltforschungsstation Schneefernerhaus (UFS) research station at an elevation of 2650 m, on the mountain top of Zugspitze, Germany. We measured the three-dimensional motion of the water droplets inside a turbulent cloud using three high-speed stationary cameras. We show the...