Propelled micro-probes in turbulence
arXiv:1802.00189 · doi:10.1103/PhysRevFluids.3.054604
Abstract
The temporal statistics of incompressible fluid velocity and passive scalar fields in developed turbulent conditions is investigated by means of direct numerical simulations along the trajectories of self-propelled point-like probes drifting in a flow. Such probes are characterised by a propulsion velocity which is fixed in intensity and direction; however, like vessels in a flow they are continuously deviated by their intended course as the result of local sweeping of the fluid flow. The recorded time-series by these moving probes represent the simplest realisation of transect measurements in a fluid flow environment. We investigate the non trivial combination of Lagrangian and Eulerian statistical properties displayed by the transect time-series. We show that, as a result of the homogeneity and isotropy of the flow, the single-point acceleration statistics of the probes follows a predictable trend at varying the propulsion speed, a feature that is also present in the scalar time-derivative fluctuations. Further, by focusing on two-time statistics we characterize how the Lagrangian-to-Eulerian transition occurs at increasing the propulsion velocity. The analysis of intermittency of temporal increments highlights in a striking way the opposite trends displayed by the fluid velocity and passive scalars.
arXiv comment12 pages, 7 figures + supplementary
References in corpus (11)
- Simulation of Rayleigh-Bénard convection using lattice Boltzmann method
- Measurement of Particle Accelerations in Fully Developed Turbulence
- Universal intermittent properties of particle trajectories in highly turbulent flows
- Droplet size distribution in homogeneous isotropic turbulence
- Microbubbles and microparticles are not faithful tracers of turbulent acceleration
- Lagrangian single particle turbulent statistics through the Hilbert-Huang Transform
- Lagrangian views on turbulent mixing of passive scalars
- Lagrangian Statistics for Navier-Stokes Turbulence under Fourier-mode reduction: Fractal and Homogeneous Decimations
- Clustering, fronts, and heat transfer in turbulent suspensions of heavy particles
- Multi-Time Multi-Scale Correlation Functions in Hydrodynamic Turbulence
- Phototactic Clustering of Swimming Micro-organisms in a Turbulent Velocity Field