Distributed dynamic phasors in empirical Galerkin models for separated flows over an airfoil

A low order Galerkin model is proposed for the flow over an airfoil. The model includes modes representing the shedding and actuation frequencies and base flow dynamics. The method addresses the difficulty of POD techniques to capture distinct harmonics in dedicated modes during transients, diminishing the link to flow physics and the efficiency of a minimal order model. Dynamic phasors representations capture transient behavior of periodic characteristics in periodically dominated systems. In a distributed variant, they are suggested as natural tools to identify and extract distinct periodic contributions to dominant modes, and are used in conjunction with subsequent POD analysis.