We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Lagrangian Time Scale of Passive Rotation for Mesoscale Particles in Turbulence
Summary
This laboratory study measured the rotation timescales of inertial rod-shaped particles in turbulent water, providing fundamental physical data on how non-spherical objects like microplastic fibers tumble in turbulent ocean environments. These timescales are important for understanding how microplastics move and mix in the sea.
Turbulence induces rotation in the living and the non-living materials in the ocean. The time scale of rotation for a living organism is important in understanding an organism's feeding efficiency, mating, prey capture rate etc. This time scale is also crucial for understanding the migration of non-living materials such as microplastics. Herein, we investigate the tumbling motion of mesoscale particles that resemble organisms of intermediate size, such as zooplankton that appear in the ocean. Using time-resolved measurements of the orientation of rigid inertial fibers in a turbulence-tank, we analyze the autocorrelation of their tumbling rate. The correlation time ($ au_d$) is well predicted by Kolmogorov inertial-range scaling based on the fiber length ($L$) when the fiber inertia can be neglected. For inertial fibers, we propose a simple model considering fiber inertia (measured by a tumbling Stokes number) and a viscous torque which accurately predicts both the correlation time and the variance of the tumbling rate. Our measurements and the theoretical model provide a basic understanding of the rotational response of an intermediately sized organism to the surrounding turbulence in its non-active state.