Optimal mode decomposition for unsteady flows

Optimal mode decomposition for unsteady flows

A new method, herein referred to as Optimal Mode Decomposition (OMD), of finding a linear model to describe the evolution of a fluid flow is presented. The method estimates the linear dynamics of a high-dimensional system which is first projected onto a subspace of a user-defined fixed rank. An iterative procedure is used to find the optimal combination of linear model and subspace that minimis...

Study of dynamics in unsteady flows using Koopman mode decomposition

The Koopman Mode Decomposition (KMD) is a data-analysis technique which is often used to extract the spatio-temporal patterns of complex flows. In this paper, we use KMD to study bifurcations of the lid-driven flow in a two-dimensional square cavity based on rigorous theorems related to the spectrum of the Koopman operator. We adopt a new computational algorithm, which is capable of detecting t...

Proper Orthogonal Decomposition Technique for Transonic Unsteady Aerodynamic Flows

A new method for constructing reduced-order models (ROM) of unsteady small-disturbance  ows is presented. The reduced-order models are constructed using basis vectors determined from the proper orthogonal decomposition (POD) of an ensemble of small-disturbance frequency-domain solutions. Each of the individual frequencydomain solutions is computed using an efŽ cient time-linearized  ow solver...

Unsteady Flows in Turbines

A Parallel Domain Decomposition Method for 3D Unsteady Incompressible Flows at High Reynolds Number

Direct numerical simulation of three-dimensional incompressible flows at high Reynolds number using the unsteady Navier-Stokes equations is challenging. In order to obtain accurate simulations, very fine meshes are necessary, and such simulations are increasingly important for modern engineering practices, such as understanding the flow behavior around high speed trains, which is the target app...