  The propulsive dynamics of a flexible undulating foil in a self-propelled
swimming configuration near a wall is studied experimentally. Measurements of
the swimming speed and the propulsive force are presented, together with image
acquisition of the kinematics of the foil and particle image velocimetry (PIV)
in its wake. The presence of the wall enhances the cruising velocity in some
cases up to 25% and the thrust by a 45%, for swept angles of 160 and 240
degrees. The physical mechanisms underlying this effect are discussed by
studying the vorticity dynamics in the wake of the foil. Proper Orthogonal
Decomposition (POD) is applied to the PIV measurements in order to analyse the
kinetic energy modal distribution in the flow and to relate it to the
propulsion generated by the foil.
