Investigation of Orthogonal Modes in High-speed Axisymmetric Jet Turbulence: Instantaneous vs. Statistical Data

We investigate orthogonal turbulence modes in a high-speed axisymmetric jet via the S-POD algorithm. We use S-POD as a barometer to gauge the energy content of the turbulence measured by its statistics vs. instantaneous flow data. Our results show that the statistics possesses modes with uniform energy distribution at low frequencies bounded by a ratio of modal energies much greater than unity, indicating that most of the auto-covariance energy is contained within a short temporal neighborhood about its auto-correlation amplitude