Turbulence characteristics of flow field around a cylindrical obstacle placed in a trapezoidal channel

This paper describes measurements of the turbulence surrounding a vertical cylinder in a steady flow. The approximate size of circulations and eddies produced by a cylindrical obstacle subject to steady flow in a trapezoidal channel are investigated. A four-component high-sampling frequency acoustic doppler velocimeter (ADV) was used to collect flow data, which were filtered using effective filtering algorithms before being processed. Because the turbulence is three dimensional, calculations were performed for all three directions. The energy distribution and dependence of the fluctuating velocities were determined and interpreted using an autocorrelation function and spectral analysis. Important turbulence statistics were calculated, including Reynolds stresses, integral time scales, and integral length scales. For representative points, the approximate size of the turbulent eddy was calculated. A spectral density function was generated and analyzed. The results show that highly coherent and dependent structures are visible in the wake vortices region for each axis..