Detailed Flow Analysis of Feedback-Channel-Type Fluidic Oscillator Using Dynamic Mode Decomposition

A fluidic oscillator, as the name suggests, emits an oscillating jet of fluid without the necessity of any moving parts. The frequency of oscillation and spread of the jet depends on the geometry as well as the dynamics of flow inside the device. The present investigation explores the internal and external flowfield behaviors exhibited by a fluidic oscillator using conventional methods and dynamic mode decomposition (DMD) analysis. A curved feedback-channel (FBC)-type fluidic oscillator of aspect ratio one is studied using two-dimensional, unsteady Reynolds-averaged Navier–Stokes (2D-URANS) simulations. The flow switching occurs due to the alternative exchange of momentum between the centerline jet and recirculating low-pressure regions in the mixing chamber. The alternating vortices outside the oscillator are produced due to the entrainment of the surrounding quiescent fluid by the oscillating jet. DMD analysis of the external flowfield reveals that most of the flow energy is associated with the highly oscillatory modes that have higher decay rates. This investigation will improve the understanding of the underlying physics of fluidic oscillators, aiding future design modifications and optimization of the size and shape of actuator geometries for various flow control applications.