2016/05/02 by Lothar Rukes, Rukes, Lothar, Moritz Sieber +4
Engineering · #Aerodynamics and Acoustics in Jet Flows #Combustion and flame dynamics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows
paper · pdf · doi:10.48550/arxiv.1605.00593
openalex publication_date 2016/05/02 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
Modal linear stability analysis has proven very successful in the analysis of\ncoherent structures of turbulent flows. Formally, it describes the evolution of\na disturbance in the limit of infinite time. In this work we apply modal linear\nstability analysis to a turbulent swirling jet undergoing a control parameter\ntransient. The flow undergoes a transition from a non-vortex breakdown state to\na state with a strong recirculation bubble and the associated global mode.\nHigh-speed Particle Image Velocimetry (PIV) measurements are the basis for a\nlocal linear stability analysis of the temporarily evolving base flow. This\nanalysis reveals that the onset of the global mode is strongly linked to the\nformation of the internal stagnation point. Several transition scenarios are\ndiscussed and the ability of a frequency selection criterion to predict the\nwavemaker location, frequency and growth rate of the global mode are evaluated.\nWe find excellent agreement between the linear global mode frequency and the\nexperimental results throughout the entire transient. The corresponding growth\nrate qualitatively conforms to experimental observations. We find no indication\nfor a nonlinear global mode as proposed by previous studies.\n