The sedimentation of small flexible and rigid fibers in structured media embedded with obstacles finds many occurrences in natural and industrial processes, such as the motion textile fibers in wastewater treatment units, wood pulp fibers in the papermaking process or the sinking of microplastics and plankton in the ocean. The aim of this project is to investigate the collective sedimentation of rigid and flexible fibers in structured media embedded with obstacles using numerical simulations. The intern will use the numerical tools developed by the supervisors’ groups. She/he will first study the collective sedimentation of flexible fibers in clear fluids to understand the effect of flexibility on the instability and the formation of clusters. She/he will then add obstacles to see how this instability is affected by their presence.