Séminaire de Mécanique d'Orsay

Le Mardi 22 septembre à 11h00 - Salle de conférences du LIMSI

Linear Feedback Control of Turbulent Channel Flow

Jonathan Finlay Morrison
Imperial College, London

A flow control strategy is proposed that addresses the problem of nonlinearity directly and ensures that the energy of any perturbation to the target profile decays monotonically so that the flow is relaminarised. The control is tested in simulated turbulent channel flow up to Re_tau=400 using full domain sensing and actuation on the wall-normal velocity. We show that the control directly counters the supply of turbulence energy arising from the interaction of the wall-normal perturbations with the flow shear. It is found that the control is only required for the larger-scale motions, specifically those above the scale of the mean streak spacing. Minimal control effort is required once laminar flow is achieved. The response of the near-wall flow is examined in detail, with particular emphasis on the pressure and wall-normal velocity fields which are attenuated significantly faster than those associated with the wall-parallel components.