Tumbling dynamics of inertial chains in extensional flow

TL;DR

This paper investigates the complex tumbling behavior of inertial chains in extensional flow through numerical simulations, revealing how chain length, Peclet, and Stokes numbers influence coil-stretch transitions and tumbling dynamics.

Contribution

It introduces a numerical study of inertial bead-rod chains in extensional flow, highlighting the non-linear dependence of coil-stretch transition and tumbling on key parameters.

Findings

Particles are trapped in coiled or stretched states at infinite chain length.

The coil-stretch transition depends non-linearly on Stokes and Peclet numbers.

Tumbling occurs near the coil-stretch transition with non-linear persistence time.

Abstract

The dynamics of elongated inertial particles in an extensional flow is studied numerically by performing simulations of freely jointed bead-rod chains. The coil-stretch transition and the tumbling instability are characterized as a function of three parameters: The Peclet number, the Stokes number and the chain length. Numerical results show that in the limit of infinite chain length, particles are trapped in a coiled or stretched state. The coil-stretch transition is also shown to depend non-linearly on the Stokes and Peclet number. Results also reveal that tumbling occurs close to the coil-stretch transition and that the persistence time is a non-linear function of Stokes and Peclet numbers.