Spiral and circular waves in the flow between a rotating and a stationary disk

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.