Transient dynamics of the wavy regime in Taylor-Couette geometry

The paper is concerned with experimental investigations of the Taylor-Couette flow between two finite length large aspect ratio concentric cylinders, with asymmetric end disturbances. The fluid sample is Newtonian and the working conditions are isothermal. The applied experimental protocol consists of a constant inner cylinder angular velocity ramp (the outer cylinder is at rest), followed by a period of 40 min with constant velocity. During this experimental time, the dynamics of the wavy regime is investigated by means of the average azimuthal amplitude, number of vortices, wave frequency and power spectra time dependences. The dimensionless ramp rate is chosen above critical rates for quasi-stationary flows used in similar studies. The results feature transient patterns of unstable wavy vortices that return in time to the simple Taylor regime or settle for two preferential states within the wavy regime. The investigation of WVF dynamics is of great importance due to the applications such as Taylor-Couette mixing-reaction devices.