Journal of Flow Visualization and Image Processing

ISSN for PRINT: 1065-3090

For Online Access

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2003, Volume10

Issue 1-2

162 pages

DOI: 10.1615/JFlowVisImageProc.v10.i12

Issue price - $280.00

Giancarlo Alfonsi
CESIC — Supercomputing Center for Computational Engineering, Fluid Dynamics Division, Università della Calabria, Via P. Bucci 22b, 87036 Rende (Cosenza), Italy

A still controversial issue in the open literature is that of the level of the kurtosis of the normal velocity fluctuations in the near-wall region of a turbulent shear flow. Numerical simulations often report values of the kurtosis considerably higher than experimental results and this fact is attributed by some authors to the different accuracy of the statistics computed from experimental series of data with respect to the numerical databases [1]. A question to be clarified is whether the high kurtosis values result from numerical artifacts of the computations or they are the manifestation of processes of physical nature related to the evolution of the turbulent flow structures near the wall [2]. In this work, experimental data of radial velocity fluctuations in turbulent pipe flow gathered with an Ultrasonic Doppler Velocimeter (UDV) are analyzed. One of the series of measurements shows a strong "sweep" of the radial velocity fluctuations and the evaluation of the related kurtosis gives a value considerably close to that reported by numerical simulations. This circumstance actually shows the occurrence of turbulent events near the wall and demonstrates the reliability of the Ultrasonic Doppler Velocimeter for turbulence measurements in fluid flows.

DOI: 10.1615/JFlowVisImageProc.v10.i12.90 Download article, 7 pages

Article price - $35.00

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