Dynamic Mode Decomposition of High Reynolds Number Supersonic Jet Flows

TL;DR

This paper uses dynamic mode decomposition on high Reynolds number supersonic jet flows simulated with large eddy simulation to identify flow structures and frequencies relevant for aeroacoustic analysis.

Contribution

It introduces a methodology combining LES and DMD for analyzing turbulent jet flows at high Reynolds numbers, linking flow structures to observed frequencies.

Findings

Identified two dominant flow frequencies linked to jet structures.

Compared LES results with existing literature for validation.

Analyzed spatial shapes of dynamic modes for different variables.

Abstract

Current design constraints have encouraged the studies of aeroacoustic fields around compressible jet flows. The present work addresses the numerical study of unsteady turbulent jet flows as a preparation for future aeroacoustic analyses of main engine rocket plumes. An in-house large eddy simulation tool is used in order to reproduce high fidelity results of compressible jet flows. The large eddy simulation formulation is written using a second order numerical scheme for a finite difference spatial discretization. Numerical simulations of perfectly expanded jets are performed and the results are compared to the literature. Dynamic mode decompositions (DMD) of the jet flow, using large size three-dimensional snapshots, are performed. Three variables are analyzed, namely, the velocity magnitude, the vorticity magnitude and the divergence of velocity. In particular, two frequencies are identified and they are linked to flow structures observed in experiments performed by other authors in the literature. The spatial shapes of the corresponding dynamic modes are also discussed.