Deformation of a flexible polymer in a random flow with long correlation time

TL;DR

This paper investigates how long temporal correlations in velocity gradients affect the deformation of flexible polymers, revealing suppression of certain dependencies and bimodal distributions in polymer elongation.

Contribution

It provides a theoretical and numerical analysis of polymer deformation in correlated flows, highlighting new behaviors in PDF distributions and transition mechanisms.

Findings

Long correlations suppress Weissenberg-number dependence in PDF tails.

FENE model shows bimodal PDF with coil-stretch transition.

Transition involves simultaneous peak changes in elongation distribution.

Abstract

The effects induced by long temporal correlations of the velocity gradients on the dynamics of a flexible polymer are investigated by means of theoretical and numerical analysis of the Hookean and FENE dumbbell models in a random renewing flow. For Hookean dumbbells, we show that long temporal correlations strongly suppress the Weissenberg-number dependence of the power-law tail characterising the probability density function (PDF) of the elongation. For the FENE model, the PDF becomes bimodal, and the coil-stretch transition occurs through the simultaneous drop and rise of the two peaks associated with the coiled and stretched configurations, respectively.