Particle-Turbulence Interactions

Abstract

In this work we examine how particle dynamics and orientation patterns can revel information about fluid structures, how particles can be used as a device to measure fluid statistics, and how in return, fluid structures interact and influence the dynamics of particles. We begin by studying the spatial field of orientations of slender fibers that are advected by a two-dimensional (2D) fluid flow. We introduce emergent scar lines as the dominant coherent structures in the orientation field of passive directors in chaotic flows. We use the standard map as a simple time-periodic two-dimensional flow that produces Lagrangian chaos. This class of flows produces persistent patterns in passive scalar advection, and we find that a different kind of persistent pattern develops in the passive director orientation field. We identify the mechanism by which emergent scar plished, I would never be where I am today without your support and love. Thank you for your patience during this time. To my father and mother whose guidance has always been a comfort in hard times. And my little brother, who is not so little anymore, has always been a place of happiness and joy.

Honeybees modify flight trajectories in turbulent wind

“…The dots were 0.5cm in diameter and 1cm apart from each other. A blank white background was used for shadow imaging of the honeybees similar to methods previously used capable of highly precise imaging and tracking of particles in turbulence [37,38]. The three cameras had different viewing angles with an overlap region which created a measurement volume of approximately 80 × 60 × 60 cm in size.…”

“…Identifying honeybees from the images and obtaining tracks was done with in-house codes based on previously used methods [37,38]. The raw images were cropped to only include sections with the white background.…”

Honeybee flight dynamics and pair separation in windy conditions near the hive entrance

“…Imaging and tracking of honeybees is based on previous methods and in-house codes used to track honeybees using consumer-grade GoPro cameras (Hejazi et al, 2022) and similar high-speed Phantom cameras used to track particles in turbulence experiments (Hejazi et al, 2019;Hejazi, 2021). An example image from one camera is shown in Fig.…”