Reynolds Stress Budget in the Near-Field of an Axisymmetric Wake in the High Reynolds Number Regime

This study presents a framework for reliable estimation of third-order turbulence statistics in the near-field of a rotationally symmetric wake (Re~70,000), with and without swirl. To achieve statistical convergence, the flow's inherent axisymmetry is leveraged by azimuthal averaging over an extensive Stereoscopic PIV dataset and increasing the number of independent realizations. A comprehensive uncertainty analysis is performed to quantify statistical and systematic uncertainties, primarily via bootstrapping methods. The approach is shown to be capable of producing reliable estimations, yielding standard errors below 10% for third-order moments. The results demonstrate that swirl breaks azimuthal symmetries, causing w-odd moments to become non-zero, thereby modifying the turbulence characteristics of the flow significantly. Analysis of axial normal Reynolds stress budget at z/D=3 shows that swirl alters the convection profile and concentrates production and transport near the wake centerline.