Effect of initial conditions on a circular jet

Two circular jets are considered. One issues from a contraction with a lami nar top-hat velocity profile. The other exits from a pipe with a fully deve loped turbulent mean velocity profile. In spite of the significantly differ ent initial conditions, spectra of axial and radial velocity fluctuations i n the far field (x greater than or similar to 30d, where d is the jet diame ter) collapse over scales ranging from the Kolmogorov length scale to a len gth scale characterizing the organized motion. This agreement is consistent with the observation that, at the measurement station, the large-scale ani sotropy is unchanged between the two flows.