Nonlinear resonances in a laminar wall jet : ejection of dipolar vortices

摘要: Nonlinear mechanisms leading to the ejection of dipolar vortices from a laminar wall jet are being investigated using highly accurate Navier-Stokes simulations. With set well-defined numerical experiments for forced Glauert jet, nonlinear resonant interaction between large-amplitude harmonic disturbance and small-amplitude wave packet is systematically explored two-dimensional Generated by pulse, experiences rapid growth in subharmonic part its spectrum resulting vortex mergings and, ultimately, pair counter-rotating jet. This instability, if not mitigated competing three-dimensional instabilities, can lead detachment entire surface. As shown direct simulations, still occurs transitional reach large amplitude level upstream region turbulent breakdown. Movies available with online version paper.