Rotational dynamics of bottom-heavy rods in turbulence from experiments and numerical simulations

• 作者: Linfeng Jiang Cheng Wang Shuang Liu Chao Sun Enrico Calzavarini
• 来源期刊: 力学快报（英文版）
• 年，卷（期）: 2021,（1）
• 页码范围: 26-31
• 页数: 6页
• 语种: 英文
• DOI: 10.3969/j.issn.2095-0349.2021.01.005

摘要

We successfully perform the three-dimensional tracking in a turbulent fluid flow of small axisymmetrical particles that are neutrally-buoyant and bottom-heavy, i.e., they have a non-homogeneous mass distribu- tion along their symmetry axis. We experimentally show how a tiny mass inhomogeneity can affect the particle orientation along the preferred vertical direction and modify its tumbling rate. The experiment is complemented by a series of simulations based on realistic Navier–Stokes turbulence and on a point-like particle model that is capable to explore the full range of parameter space characterized by the gravi- tational torque stability number and by the particle aspect ratio. We propose a theoretical perturbative prediction valid in the high bottom-heaviness regime that agrees well with the observed preferential ori- entation and tumbling rate of the particles. We also show that the heavy-tail shape of the probability distribution function of the tumbling rate is weakly affected by the bottom-heaviness of the particles.