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原文传递 Vorticity and Turbulence in the Wake of a Bridge Pier.

题名：	Vorticity and Turbulence in the Wake of a Bridge Pier.
作者：	lien, r. c. sanford, t. b.
关键词：	vibration, vortices, vertical orientation, reynolds number, horizontal orientation, kinetic energy, probability density functions, autocorrelation
摘要：	Dissipation rates of turbulence kinetic energy and enstrophy are reported in a high Reynolds number turbulent wake. Our results represent a set of rare field observations of vorticity and turbulence in a turbulent wake with a high Reynolds number, The turbulent wake was formed by an unsteady strong tidal current interacting with a bridge pier. Measurements were taken in the intermediate wake. Both energy and enstrophy show a similar downstream decay rate faster than that predicted by the self preservation similarity in the far wake. The theoretical relation for high Reynolds number flow is confirmed by field observations. The magnitudes of the vertical and horizontal components of enstrophy are not significantly different. Probability density functions of normalized vorticity components and of the dissipation rate of turbulence kinetic energy are nearly identical to each other. They are also nearly identical to the empirical function found in laboratory experiments. The turbulence internal intermittency is -0.2, estimated from autocorrelation coefficients of enstrophy; this value is close to that reported previously in turbulent wakes and jets. / NOTE: Final technical rept. 1 Oct 2003-30 Sep 2006. / Supplementary Notes: Submitted to IEEE Jnl. of Engineering, Jan 2008. / Availability Note: Product reproduced from digital image. Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA.
总页数：	u0816；29p
报告类型：	科技报告