  We report experimental measurements of inertial waves generated by an
oscillating cylinder in a rotating fluid. The two-dimensional wave takes place
in a stationary cross-shaped wavepacket. Velocity and vorticity fields in a
vertical plane normal to the wavemaker are measured by a corotating Particule
Image Velocimetry system. The viscous spreading of the wave beam and the
associated decay of the velocity and vorticity envelopes are characterized.
They are found in good agreement with the similarity solution of a linear
viscous theory, derived under a quasi-parallel assumption similar to the
classical analysis of Thomas and Stevenson [J. Fluid Mech. 54 (3), 495-506
(1972)] for internal waves.
