A model for alignment between microscopic rods and vorticity

Abstract

Numerical simulations show that microscopic rod-like bodies suspended in a turbulent flow tend to align with the vorticity vector, rather than with the dominant eignevector of the strain-rate tensor. This paper investigates an analytically solvable limit of a model for alignment in a random velocity field with isotropic statistics. The vorticity varies very slowly and the isotropic random flow is equivalent to a pure strain with statistics which are axisymmetric about the direction of the vorticity. We analyse the alignment in a weakly fluctuating uniaxial strain field, as a function of the product of the strain relaxation time ${\tau }_{\mathrm{s}}$ and the angular velocity $\omega$ about the vorticity axis. We find that when $\omega {\tau }_{\mathrm{s}}\gg 1$, the rods are predominantly either perpendicular or parallel to the vorticity.

References in corpus (2)

• Orientation of non-spherical particles in an axisymmetric random flow
• A microfluidic device for the study of the orientational dynamics of microrods

Cited by in corpus (7)

• Alignment of vorticity and rods with Lagrangian fluid stretching in turbulence
• Tumbling of small axisymmetric particles in random and turbulent flows
• Measurements of the Solid-body Rotation of Anisotropic Particles in 3D Turbulence
• Orientation dynamics of small, triaxial-ellipsoidal particles in isotropic turbulence
• Orientation of non-spherical particles in an axisymmetric random flow
• Aperiodic tumbling of microrods advected in a microchannel flow
• Elliptical Tracers in Two-dimensional, Homogeneous, Isotropic Fluid Turbulence: the Statistics of Alignment, Rotation, and Nematic Order