The effect of Reynolds number on a turbulent far-wake

The turbulent far-waked generated by a circular cylinder is investigated for two values (1350 and 4600) of the Reynolds number Re(theta) (based on the free stream velocity and the momentum thickness). Two arrays of sixteen X-wires, eight in the (x,y)-plane and eight in the (x,z)-plane, are used to capture the main features of the large-scale motion in two orthogonal planes. Both the magnitude of the measured Reynolds stresses and the size of the two-point velocity and vorticity correlation contours increase with Reynolds number. The probability density function and spectra of the velocity signals also exhibit differences with Re(theta). A comparison of centerline turbulence intensities with those in the literature suggests that the Reynolds number dependence may disappear for Re(theta) greater than or equal to 5000.