Mean and Unsteady Flow Reconstruction Using Data-Assimilation and Resolvent Analysis
A methodology is presented that exploits both data-assimilation techniques and resolvent analysis for reconstructing turbulent flows, containing organized structures, with an efficient set of measurements. The mean (time-averaged) flow is obtained using variational data-assimilation that minimizes the discrepancy between a limited set of flow measurements, generally from an experiment, and a numerical simulation of the Navier–Stokes equations. The fluctuations are educed from resolvent analysis and time-resolved data at a single point in the flow. Resolvent analysis also guides where measurements of the mean and fluctuating quantities are needed for efficient reconstruction of a simple example case study: flow around a circular cylinder at a Reynolds number of Re=100. For this flow, resolvent analysis reveals that the leading singular value, most amplified modes, and the mean profile for 47
© 2019 by the American Institute of Aeronautics and Astronautics, Inc. Received 6 September 2018; revision received 20 February 2019; accepted for publication 2 April 2019; published online 24 May 2019. The authors would like to acknowledge financial support from U.S. Air Force Office of Scientific Research grant number FA 9550-16-1-0361, Army Research Office grant number W911NF-17-1-0306, and Office of Naval Research grant number N0014-17-1-3022.