Wake-boundary layer interaction behind an elliptic cylinder at different Reynolds numbers. Issue 7 (3rd July 2018)

• Record Type: Journal Article
• Authors: Ezadi Yazdi, Mohammad Javad; Bak Khoshnevis, Abdulamir
• Is Part Of: Journal of turbulence. Volume 19:Issue 7(2018)
• Page Start: 529
• Page End: 552
• Publication Date: 2018-07-03
• Subjects: Wake-boundary layer interaction -- elliptic cylinder -- Strouhal number -- hot-wire anemometry; Turbulence -- Periodicals; Turbulence -- Périodiques; 532.0527
• DOI: 10.1080/14685248.2018.1472382
• Languages: English
• ISSNs: 1468-5248

Abstract

ABSTRACT: In this paper, hot-wire anemometry (HWA) is used to experimentally investigate interactions between a fully developed turbulent boundary layer and wake of an elliptic cylinder where axis ratio (AR) of the cylinder is 2. The elliptic cylinder was located inside and outside a turbulent boundary layer with a thickness (δ) of 0.38 B . Furthermore, experiments were conducted at different Reynolds numbers (13, 250 and 26, 500) based upon the smallest cylinder diameter ( B ). Mean velocity, turbulence intensity and higher-order central moments of velocity signals (i.e. skewness and flatness) measurements were performed using HWA upon wake-boundary layer interactions on a flat plate. Results showed that profiles of stream-wise mean velocity and turbulence intensity were greatly dependent on gap ratio ( G / B ) and Reynolds number (Re) in near-wake region. It was also observed that, except for G / B = 0.1, the wake-boundary layer interactions were faster at Reynolds number of 26, 500 rather than 13, 250. The interactions occurred earlier upon fluctuating the velocity rather than the case where a fixed mean velocity was considered. The results further show that an increase in the gap ratio increases Strouhal number almost independent of δ/ B . Behind the cylinder, relatively smaller wake region was obtained at Re = 26, 500 rather than Re = 13, 250, where the velocity profiles quickly converged to the flat plate boundary layer velocity profiles.