2018/04/22 by Marek Morzyński, Morzynski, Marek, Wojciech Szeliga +3
Engineering · Physics and Astronomy · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Fluid Dynamics and Vibration Analysis #Hydraulic and Pneumatic Systems #Iterative Learning Control Systems #Model Reduction and Neural Networks #Plasma and Flow Control in Aerodynamics
paper · pdf · doi:10.48550/arxiv.1804.08113
openalex publication_date 2018/04/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We advance the computation of physical modal expansions for unsteady\nincompressible flows. Point of departure is a linearization of the\nNavier-Stokes equations around its fixed point in a frequency domain\nformulation. While the most amplified stability eigenmode is readily identified\nby a power method, the technical challenge is the computation of more damped\nhigher-order eigenmodes. This challenge is addressed by a novel method to\ncompute unstable periodically forced solutions of the linearized Navier-Stokes\nsolution. This method utilizes two key enablers. First, the linear dynamics is\ntransformed by a complex shift of the eigenvalues amplifying the flow response\nat the given frequency of interest. Second, the growth rate is obtained from an\niteration procedure. The method is demonstrated for several wake flows around a\ncircular cylinder, a fluidic pinball, i.e. the wake behind a cluster of\ncylinders, a wall-mounted cylinder, a sphere and a delta wing. The example of\nflow control with periodic wake actuation and forced physical modes paves the\nway for applications of physical modal expansions. These results encourage\nGalerkin models of three-dimensional flows utilizing Navier-Stokes based modes.\n