MINES ParisTech CAS - Centre automatique et systèmes


Séance du jeudi 22 juin 2017, Salle L106, 14h00-16h00.

15h00-16h00 - Thomas Chambrion, Esstin, Université de Lorraine, France

A swimmer is an animal surrounded by a fluid. When the swimmer applies some force on the fluid, the reaction leads to a change in the acceleration of the swimmer. With suitable shape changes, the swimmer can then reach any point in the fluid (it swims). This talk focuses on the linear swimmers, that is fluid-structure systems where the acceleration of the swimmer is a linear function of the velocity of the change of its shape. This is the case for instance for bacteria in viscous fluids (Stokes flows). In this framework it can be shown that for a large class of physically reasonable costs, optimal strokes do exist (achieving the largest moves with a given cost). Moreover, some examples exhibit counter-intuitive behaviours, such as the on-monotonicity of the cost with respect to the motion: it is sometimes cheaper to reach a further point.