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Skin-friction drag reduction in turbulent flows: how to set up the flow control problem

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  • UserMaurizio Quadrio (Department of Aerospace Sciences and Technologies, Politecnico di Milano)
  • ClockThursday 20 June 2019, 11:00-12:00
  • HouseLR3A, CUED.

If you have a question about this talk, please contact Amélie Lamarquette.

The talk will describe the rational set up of a fundamental flow control problem, where active flow control is used to reduce turbulent skin-friction drag in an indefinite plane channel. The proper way of accounting for the energy cost of the control, as well as the cor- rect objective function in an optimization procedure, will be identified and discussed. The framework builds upon the Constant Power Input (CPI) concept, that we have re- cently introduced as a viable alternative to compare different flows under flow control. With CPI , at statistical equilibrium each flow has the same global energy flux per unit time, hence the same total energy dissipation rate. A new decomposition of the total dissipation is introduced, stemming from an ex- tended Reynolds decomposition, where the mean velocity is split into a laminar com- ponent and a deviation from it. The figure below shows for the most general case the different energy fluxes of Mean Kinetic Energy (MKE) and Turbulent Kinetic Energy (TKE).

This talk is part of the Fluid Mechanics (CUED) series.

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