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Mean and unsteady flow reconstruction using data-assimilation and resolvent analysis

Mean and unsteady flow reconstruction using data-assimilation and resolvent analysis
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 < Re < 320 scale with the shedding frequency and length of the recirculation bubble. A relationship between these two parameters reinforces the notion that a wave maker, for which the length scales with the recirculation bubble, determines the frequency and region where an instability mechanism is active. The procedure offers a way to choose sensor locations that capture the main coherent structures of a flow and a method for computing mean pressure by using correctly weighted resolvent modes.

0001-1452
575-588
Symon, Sean
2e1580c3-ba27-46e8-9736-531099f3d850
Sipp, Denis
58cb1e91-b79e-4efe-aef6-929384921418
Schmid, Peter J.
67225b59-07a3-4ea8-b65b-df8bb6a17ecd
McKeon, Beverley J.
4623066f-492f-4944-a541-151a6a130402
Symon, Sean
2e1580c3-ba27-46e8-9736-531099f3d850
Sipp, Denis
58cb1e91-b79e-4efe-aef6-929384921418
Schmid, Peter J.
67225b59-07a3-4ea8-b65b-df8bb6a17ecd
McKeon, Beverley J.
4623066f-492f-4944-a541-151a6a130402

Symon, Sean, Sipp, Denis, Schmid, Peter J. and McKeon, Beverley J. (2020) Mean and unsteady flow reconstruction using data-assimilation and resolvent analysis. AIAA Journal, 58 (2), 575-588. (doi:10.2514/1.J057889).

Record type: Article

Abstract

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 < Re < 320 scale with the shedding frequency and length of the recirculation bubble. A relationship between these two parameters reinforces the notion that a wave maker, for which the length scales with the recirculation bubble, determines the frequency and region where an instability mechanism is active. The procedure offers a way to choose sensor locations that capture the main coherent structures of a flow and a method for computing mean pressure by using correctly weighted resolvent modes.

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More information

Accepted/In Press date: 2 April 2019
e-pub ahead of print date: 24 May 2019
Published date: February 2020

Identifiers

Local EPrints ID: 444883
URI: http://eprints.soton.ac.uk/id/eprint/444883
ISSN: 0001-1452
PURE UUID: cb0c8e7d-4b1c-4796-932f-3c5c792a8ac1

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Date deposited: 09 Nov 2020 17:32
Last modified: 14 Sep 2021 19:47

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Contributors

Author: Sean Symon
Author: Denis Sipp
Author: Peter J. Schmid
Author: Beverley J. McKeon

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