Particle-fluid interaction forces as the source of acceleration PDF invariance in particle size

TL;DR

This study demonstrates that particle-fluid interaction forces explain the invariance of acceleration probability density functions in small particles within turbulent flows, highlighting the role of lift forces in suspension.

Contribution

It provides experimental evidence linking particle-fluid interaction forces to the invariance of acceleration PDFs in turbulent suspensions, emphasizing the significance of lift forces.

Findings

Invariance of acceleration PDFs extends to component forces.

Particle-fluid interaction forces maintain suspension.

Lift forces are significant in particle dynamics.

Abstract

The conditions allowing particle suspension in turbulent flow are of interest in many applications, but understanding them is complicated both by the nature of turbulence and by the interaction of flow with particles. Observations on small particles indicate an invariance of acceleration PDFs of small particles independent of size. We show to be true the postulated role of particle/fluid interaction forces in maintaining suspension. The 3D-PTV method, applied for two particle phases (tracers and inertial particles) simultaneously, was used to obtain velocity and acceleration data, and through the use of the particle's equation of motion the magnitude of forces representing either the flow or the particle interaction were derived and compared. The invariance of PDFs is shown to extend to the component forces, and lift forces are shown to be significant.