Tumbling of Inertial Fibers in Turbulence

Area of Science:

• Fluid Dynamics
• Turbulence
• Particle Dynamics

Background:

• Anisotropic particles are crucial in environmental and industrial turbulent flows.
• Modeling particle rotation dynamics presents a significant challenge with industrial implications, e.g., in papermaking.

Purpose of the Study:

• Investigate the rotation rate of neutrally buoyant fibers exceeding the Kolmogorov length.
• Understand the impact of fiber inertia on rotation dynamics.
• Develop a predictive model for fiber rotation in turbulent flows.

Main Methods:

• Numerical simulations of turbulent flows with anisotropic particles.
• Analysis of fiber rotation rates based on particle properties.
• Development of a theoretical model for fiber inertia effects.

Main Results:

• Fiber inertia was identified as the cause for a reduced rotation rate.
• A novel model accurately describes the observed decrease in rotation rate.
• A new Stokes number was introduced to delineate the limits of the slender body approximation.

Conclusions:

• Fiber inertia significantly influences rotation dynamics in turbulent flows.
• The proposed model offers improved prediction capabilities for anisotropic particle behavior.
• The new Stokes number provides a critical parameter for analyzing slender body approximations.