# Driven spheres, ellipsoids and rods in explicitly modeled polymer solutions

## TL;DR

This study uses simulations to analyze how driven particles of various shapes move through polymer solutions, revealing polymer depletion effects that enhance particle velocities beyond classical predictions.

## Contribution

It introduces a detailed simulation approach to understand driven particle transport in polymer solutions, highlighting the role of polymer depletion zones and slip velocities.

## Key findings

- Particles move faster than Stokes law predicts due to polymer depletion.
- Polymer-depleted regions cause apparent slip velocities around particles.
- A two-layer fluid model accurately describes the flow and transport phenomena.

## Abstract

Understanding the transport of driven nano- and micro-particles in complex fluids is of relevance for many biological and technological applications. Here we perform hydrodynamic multiparticle collision dynamics simulations of spherical and elongated particles driven through polymeric fluids containing different concentrations of polymers. We determine the mean particle velocities which are larger than expected from Stokes law for all particle shapes and polymer densities. Furthermore we measure the fluid flow fields and local polymer density and polymer conformation around the particles. We find that polymer-depleted regions close to the particles are responsible for an apparent tangential slip velocity which accounts for the measured flow fields and transport velocities. A simple two-layer fluid model gives a good match to the simulation results.