We consider the motion of a rigid body immersed in a two-dimensional irrotational
perfect incompressible fluid. The fluid is governed by the Euler equation,
while the trajectory of the solid is given by Newton’s equation, the force
term corresponding to the fluid pressure on the body’s boundary only. The
system is assumed to be confined in a bounded domain with an impermeable
condition on a part of the external boundary. The issue considered here is the
following: is there an appropriate boundary condition on the remaining part of
the external boundary (allowing some fluid going in and out the domain)
such that the immersed rigid body is driven from some given initial position
and velocity to some final position (in the same connected component of
the set of possible positions as the initial position) and velocity in a given
positive time, without touching the external boundary? In this paper we
provide a positive answer to this question thanks to an impulsive control
strategy. To that purpose we make use of a reformulation of the solid equation
into an ODE of geodesic form, with some force terms due to the circulation
around the body, as used by Glass, Munnier and Sueur (Invent. Math. 214:1
(2018), 171–287), and some extra terms here due to the external boundary
control.
Keywords
fluid-solid interaction, impulsive control, geodesics,
coupled ODE/PDE system, fluid mechanics, Euler equation,
control problem, external boundary control