Polymer rheology simulations at the meso- and macroscopic scale

TL;DR

This paper demonstrates that dissipative particle dynamics can simultaneously simulate polymer rheology at mesoscopic and macroscopic scales, capturing flow instabilities and visco-elastic behavior with a novel dumbbell model.

Contribution

It introduces a DPD-based model incorporating dumbbells to accurately simulate polymer visco-elasticity and flow behavior at multiple scales, including turbulence effects.

Findings

Model reproduces known polymer stretching and tumbling statistics.

Increased polymer fraction delays turbulence onset in shear flows.

Method enables modeling complex rheological conditions with coarse-grained polymers.

Abstract

We show that simulations of polymer rheology at a fluctuating mesoscopic scale and at the macroscopic scale where flow instabilities occur can be achieved at the same time with dissipative particle dynamics (DPD) technique.} We model the visco-elasticity of polymer liquids by introducing a finite fraction of dumbbells in the standard DPD fluid. The stretching and tumbling statistics of these dumbbells is in agreement with what is known for isolated polymers in shear flows. At the same time, the model exhibits behaviour reminiscent of drag reduction in the turbulent state: as the polymer fraction increases, the onset of turbulence in plane Couette flow is pushed to higher Reynolds numbers. The method opens up the possibility to model nontrivial rheological conditions with ensuing coarse grained polymer statistics.