Abonnement à la biblothèque: Guest
Fifth International Symposium on Turbulence and Shear Flow Phenomena
August, 27-29, 2007, Technische Universität München, Munich, Germany

DOI: 10.1615/TSFP5

EFFECTS OF FLOW SCALE ON THE INTERMITTENT PROPERTIES OF A SINGLE STREAM SHEAR LAYER

pages 1181-1186
DOI: 10.1615/TSFP5.1840
Get accessGet access

RÉSUMÉ

A four-sensor vorticity (ωz) probe has been used to characterize the external intermittency in a self-preserving single-stream shear layer at two downstream locations: x/θo = 200, 500. The algorithm to define intermittency state as "on" (the mixed, "interior" fluid of the shear layer) or "off" (the exterior fluid of the sheared region's adjacent potential streams) is based on the "activity level" of the ωz(t) time series. This discrimination technique leads to a intermittency time series, I(t), with well-defined 1, 0 states for the interior and exterior states, respectively. This time series allows conditional statistics for the velocity components to be acquired. Relatively minor differences are observed for the statistical values at the two downstream locations, except for a distinctly lower mean intermittency at x/θo = 500. A distinctive result, revealed by the joint histogram of u', v' for the inactive fluid, is the clear evidence for separate "wedges" of inactive fluid from both the high-speed and low-speed sides of the shear layer. Direct comparisons are made to the 1970 results of Wygnanski and Fiedler.

Portail numérique Bibliothèque numérique eBooks Revues Références et comptes rendus Collections Prix et politiques d'abonnement Begell House Contactez-nous Language English 中文 Русский Português German French Spain