Spectral analysis of temporally resolved velocity field data for Taylor-Couette flow

High speed stereoscopic particle image velocimetry (PIV) data were collected for Taylor-Couette flow for flow regimes varying from wavy through turbulent. The Taylor-Couette apparatus used had an aspect ratio of 34 and a radius ratio of 0.733. The working fluid was an index-of-refraction matched sodium iodide and water solution. Data were obtained for rotational Reynolds numbers ranging from 6 up to 200. Each high speed PIV data set consisted of 2048 images separated in times ranging from 1/60 through 1/2000 second as required by the rotational Reynolds number observed. The time resolved velocity field data were subjected to Fourier Decomposition to find the frequency behavior for a given rotational Reynolds number by calculating the power spectral density. For each investigated rotational Reynolds number, several data sets were averaged together to reduce the effect of observational ``noise.'' Turbulent kinetic energy and Reynolds Stresses were also calculated for the turbulent flow cases. Data at different rotational Reynolds numbers are compared to characterize flow transitions.