Identifying dynamic modes of separated flow subject to ZNMF-based control from surface pressure measurements

Eric Deem, Louis Cattafesta, Hao Zhang, Clarence Rowley, Maziar Hemati, Francois Cadieux, Rajat Mittal

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations


Fluid systems are most efficient for fully attached flows, and designers therefore seek to avoid flow separation. Active flow control can help achieve this goal, and closed-loop control offers improved performance at off-design conditions. However, this requires feedback of accurate state estimates to the controller in real time. This motivates a physics-based, state-estimation technique that economically extracts key dynamical features of the flow. This work aims to extract dynamical characteristics of a laminar separation bubble on a flat plate at a chord Reynolds number of 105 using a linear array of unsteady surface pressure measurements. First, DynamicMode Decomposition (DMD) is employed on high-dimensional time-resolved PIV velocity and corresponding estimated pressure fields to identify the dynamically relevant spatial structure and temporal characteristics of the separated flow. Then, results are presented of various open-loop control cases using pulse-modulation of a zero-net mass-flux actuator slot located just upstream of separation. Real-time estimates of the dynamical characteristics are provided by performing on- line DMD onmeasurements froma linear array of 13 unsteady surface pressure transducers. The results show that this method provides reliable estimates of the modal characteristics of the sep- arated flow subject to forcing at a rate much faster than the characteristic time scales of the flow. Therefore, online DMD applied to the surface pressure measurements provides a time-varying linear estimate of the evolution of the controlled flow, thereby enabling closed-loop control.

Original languageEnglish (US)
Title of host publication47th AIAA Fluid Dynamics Conference, 2017
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624105005
StatePublished - 2017
Event47th AIAA Fluid Dynamics Conference, 2017 - Denver, United States
Duration: Jun 5 2017Jun 9 2017

Publication series

Name47th AIAA Fluid Dynamics Conference, 2017


Other47th AIAA Fluid Dynamics Conference, 2017
Country/TerritoryUnited States

Bibliographical note

Funding Information:
Funding for this work is provided under AFOSR Grant FA9550-14-1-0289, monitored by Dr. Doug Smith.

Publisher Copyright:
© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


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