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Drag reduction in channel flow using nonlinear controlTwo nonlinear control schemes have been applied to the problem of drag reduction in channel flow. Both schemes have been tested using numerical simulations at a mass flux Reynolds numbers of 4408, utilizing 2D nonlinear neutral modes for goal dynamics. The OGY-method, which requires feedback, reduces drag to 60-80 percent of the turbulent value at the same Reynolds number, and employs forcing only within a thin region near the wall. The H-method, or model-based control, fails to achieve any drag reduction when starting from a fully turbulent initial condition, but shows potential for suppressing or retarding laminar-to-turbulent transition by imposing instead a transition to a low drag, nonlinear traveling wave solution to the Navier-Stokes equation. The drag in this state corresponds to that achieved by the OGY-method. Model-based control requires no feedback, but in experiments to date has required the forcing be imposed within a thicker layer than the OGY-method. Control energy expenditures in both methods are small, representing less than 0.1 percent of the uncontrolled flow's energy.
Document ID
19930062840
Document Type
Conference Paper
Authors
Keefe, Laurence R. (Nielsen Engineering and Research, Inc. Mountain View, CA, United States)
Date Acquired
August 16, 2013
Publication Date
July 1, 1993
Subject Category
FLUID MECHANICS AND HEAT TRANSFER
Report/Patent Number
AIAA PAPER 93-3279
Meeting Information
AIAA, Shear Flow Conference(Orlando, FL)
Funding Number(s)
CONTRACT_GRANT: NAS1-19643
Distribution Limits
Public
Copyright
Other