Circular and spiral waves are observed in the flow between a rotating and a
stationary disk. These waves are generated by instabilities of the station
ary disk boundary layer. This experimental work is devoted to their study b
y means of flow visualization and measurements of the associated velocity f
ields. In particular, instantaneous velocity profiles are measured by ultra
sonic Doppler anemometry. The spatio-temporal characteristics of the waves
are studied with the help of Fourier transforms of these velocity signals.