Orientation of non-spherical particles in an axisymmetric random flow

TL;DR

This paper analytically investigates how non-spherical particles orient themselves in an axisymmetric random flow, revealing four distinct behavioral regimes based on flow anisotropy and particle shape.

Contribution

It provides an exact calculation of the stationary orientation distribution and identifies four regimes of particle motion in anisotropic flows.

Findings

Four regimes of particle orientation behavior identified

Exact stationary orientation distribution derived

Flow anisotropy and particle shape determine motion regimes

Abstract

The dynamics of non-spherical rigid particles immersed in an axisymmetric random flow is studied analytically. The motion of the particles is described by Jeffery's equation; the random flow is Gaussian and has short correlation time.The stationary probability density function of orientations is calculated exactly. Four regimes are identified depending on the statistical anisotropy of the flow and on the geometrical shape of the particle. If {\lambda} is the axis of symmetry of the flow, the four regimes are: rotation about {\lambda}, tumbling motion between {\lambda} and -{\lambda}, combination of rotation and tumbling, and preferential alignment with a direction oblique to {\lambda}.