Soft Matter and Complex Systems Seminar

Sedimentation of elastic objects of different shapes in viscous fluids remains an active research topic due to the importance of such phenomena in numerous biological systems and technological processes. However, even the sedimentation of basic objects, such as fibers or loops, can display rich dynamics if structural flexibility is allowed. This study presents a numerical investigation of the sedimentation of a highly elastic fiber under gravity in a very viscous fluid. We employ the bead model and multipole expansion of the Stokes equations, corrected for lubrication that is implemented in the precise Hydromultipole numerical codes. A dimensionless elasto-gravitation number B, which relates the gravitation and bending forces acting on the fiber, and the fiber aspect ratio N are used to describe the fiber’s flexibility. The fiber evolution is monitored over an extended period to identify the attracting modes by systematically varying B and N in a wide range. An analysis of the characteristic features, such as characteristic time scales and fiber deformation patterns, of all the identified attracting modes is presented. The created phase diagram of these modes clearly illustrates that the existence of each mode depends not only on the elasto-gravitation number B but also on the fiber's aspect ratio N.