Spatiotemporal pattern modulations in the Taylor-Dean system

Flow between two horizontal coaxial cylinders with a partially filled gap is investigated for the case when the primary instability forms a pattern of traveling inclined rolls which is simply periodic in space and time. Slightly above the onset, there is a second instability which results in a periodic modulation of the rolls with an axial wavelength of {~}3 rolls and a lower frequency. Both the traveling inclined rolls and the {~}3 roll modulation pattern exhibit long-wavelength low-frequency phase modulations and associated defects.