The far downstream evolution of the high-Reynolds-number axisymmetric wake behind a disk. Part 1. Single-point statistics

The high-Reynolds-number axisymmetric wake behind a disk has been studied for 10 ≤ x/D ≤ 150 (36 ≤ x/θ ≤ 552) using a rake of 15 hot wires. The disk had a diameter of 20 mm, and the Reynolds number based on the free-stream velocity was 26 400. Mean velocity profiles, root-mean-square profiles, and power spectra are presented. By using regression techniques to fit the velocity profiles it was possible to obtain accurate velocity centreline deficits and transverse length scales to even the last downstream position. Beyond the initial region which extends to x/D=30, the data are in excellent agreement with the high-Reynolds-number equilibrium similarity solution.