Dynamics of squirmers in explicitly modeled polymeric fluids

Biological microswimmers such as bacteria and sperm cells often encounter complex biological fluid environments. Here we use the well-known squirmer microswimmer model to show the importance of the local fluid microstructure and non-continuum effects on their swimming speed in different polymeric and filamentous fluids. Surprisingly, we find that different squirmer types move at considerably different speed in filamentous fluids which cannot be explained by existing continuum models, but by considering the local fluid and polymer properties around the squirmers. Furthermore, direct squirmer-polymer interactions slow down in particular pushers by trapping large stiff filaments in a self-generated recirculation region in front of them.