Dynamics of a polymer under multi-gradient fields

TL;DR

This study uses generalized Langevin dynamics simulations to explore how multi-gradient fields influence polymer transport, revealing scaling laws, distribution behaviors, and temperature-dependent phenomena.

Contribution

It introduces a detailed analysis of polymer tumbling dynamics under combined gradient fields, highlighting new scaling laws and behaviors at different temperatures and flow conditions.

Findings

Tumbling frequency scales as Wi^{0.66}.

Angular tumbling time distribution exhibits exponential tail and deviates from Poisson at high Wi.

At low temperature, decay rate decreases with Wi at intermediate shear rates.

Abstract

Effects of multi-gradient fields on the transport of a polymer chain have been investigated by using generalized Langevin dynamics simulations. We observe that the natural frequency of tumbling follows $Wi^{0.66}$ scaling, where $Wi$ is the Weissenberg number. Analysis of angular tumbling time distribution reveals that the tail of distribution follows exponential distribution and at high Weissenberg number, deviates from Poisson behaviour. Competition between velocity gradient which results shear flow in the system, and solvent quality gradient arising due to the interaction among monomers revealed that there is another scaling associated with the angular tumbling time distribution. Moreover, at low temperature, we observe unusual behaviour that at intermediate shear rates, decay rate $\nu$ decreases with $Wi$.