Self-regulating non-equilibrium in a slender body’s turbulent wake

We study transverse profiles and time fluctuations of turbulence dissipation rate, turbulence kinetic energy and integral length scales by means of high-speed stereoscopic particle image velocimetry in the turbulent wake of a 6 : 1 prolate spheroid that has its principal axis aligned with the incoming non-turbulent flow. This turbulent wake of a slender body differs from turbulent bluff body wakes in terms of transverse non-homogeneity of turbulence dissipation rate and because it is not axisymmetric even though it nominally is. Even so, both transverse profiles and time fluctuations of turbulence dissipation rate coefficients (inverse ratio between the rate with which the large scales lose energy and the rate with which the small scales dissipate energy) and of the Taylor length-based Reynolds number (ratio between the turbulent kinetic energy mostly in the large scales and the turbulent kinetic energy at the smallest scales) obey self-regulating non-equilibrium, as previously found in various other turbulent flows. However, the power law relating the transverse variations and the time fluctuations of these two ratios differs from previously reported self-regulating non-equilibrium power law scalings in other turbulent flows.