This article aims at studying the controllability of a simplified fluid structure
interaction model derived and developed in [C. Conca, J. Planchard and M. Vanninathan,
RAM: Res. Appl. Math. John Wiley & Sons Ltd., Chichester (1995);
J.-P. Raymond and M. Vanninathan, ESAIM: COCV 11 (2005)
180–203; M. Tucsnak and M. Vanninathan, Systems Control Lett. 58
(2009) 547–552]. This interaction is modeled by a wave equation surrounding a
harmonic oscillator. Our main result states that, in the radially symmetric case, this
system can be controlled from the outer boundary. This improves previous results [J.-P.
Raymond and M. Vanninathan, ESAIM: COCV 11 (2005) 180–203;
M. Tucsnak and M. Vanninathan, Systems Control Lett. 58
(2009) 547–552]. Our proof is based on a spherical harmonic decomposition of the
solution and the so-called lateral propagation of the energy for 1d waves.