Analysis of the trajectories of falling porous objects

Type: Semester project

We are accustomed to seeing objects fall into a fluid on an almost daily basis. From leaves of trees or sheets of paper sliding in the air to objects sinking in water; common situations where an object interacts with the fluid around it and where, depending on the physical parameters, various falling regimes can be observed, such as fluttering (Fig. 1a) or tumbling (Fig. 1b). Apart from everyday situations, falling objects represent a starting point for more practical interests in engineering or biomechanics, for example.

This project aims at studying experimentally the effect of permeability and porosity in the falling regimes of porous objects. The student will use the experimental set-up already built to study the trajectories of falling porous objects and investigate the effect of parameters such as permeability, porosity, density and inertia of the material, Archimedes number, etc.  Although some of the porous plates are already available (Fig. 1c)), a work of conception will be developed by the student to imagine new patterns to explore all possible scenarios.

Fig. 1. a) Fluttering and b) tumbling regime of a falling paper. Figure from Belmonte, Eisenberg and Moses, Physical Review Letters, 1998. c) Experimental plates to assess the effect of permeability and porosity in the falling regimes. We have drilled different patterns of holes to change the characteristics of these porous objects, as well as used different materials and thicknesses for the plates.

Supervisors: Jesus Sanchez Rodriguez & François Gallaire