Fractional Mode Numbers in Wavy Taylor Vortex Flow

Spectral power and phase measurements are presented which demonstrate the existence of a wavy Taylor vortex-flow state with a mode number m=3/2. The mode is periodically continued around the annulus by a phase anomaly which is stationary in the laboratory frame. It is also shown that wavy Taylor vortex flow results in an increase (decrease) of the Taylor vortex-pair width near the center (ends) of the apparatus.