Wake-driven dynamics of finite-sized buoyant spheres in turbulence

TL;DR

This study experimentally investigates how buoyant spheres in turbulence exhibit complex dynamics influenced by wake effects, revealing that particle size and density differences significantly alter acceleration behavior, challenging existing models.

Contribution

The paper demonstrates that wake-induced forces significantly impact buoyant sphere dynamics in turbulence, highlighting the need for models that incorporate multi-physics effects.

Findings

Acceleration variance increases with particle size due to wake effects

Small density reductions cause strong modifications in particle dynamics

Current models underestimate wake contributions in buoyant particle behavior

Abstract

Particles suspended in turbulent flows are affected by the turbulence and at the same time act back on the flow. The resulting coupling can give rise to rich variability in their dynamics. Here we report experimental results from an investigation of finite-sized buoyant spheres in turbulence. We find that even a marginal reduction in the particle's density from that of the fluid can result in strong modification of its dynamics. In contrast to classical spatial filtering arguments and predictions of particle models, we find that the particle acceleration variance increases with size. We trace this reversed trend back to the growing contribution from wake-induced forces, unaccounted for in current particle models in turbulence. Our findings highlight the need for improved multi-physics based models that account for particle wake effects for a faithful representation of buoyant-sphere dynamics in turbulence.