Active Turbulence Control in Wall Bounded Flows Using Direct Numerical Simulation

摘要

The objective of the study is to explore concepts for control of turbulentboundary layers leading to skin-friction reduction using the direct numerical simulation technique. This report is divided into three parts where different control methods are investigated: an active control by sensing and perturbing structures near the wall, a feedback control procedure guided by control theory, and a passive control by longitudinal riblets. Part I: significant drag reduction is achieved when the surface boundary condition is modified to suppress the dynamically significant coherent structures present in the wall region. Part II: mathematical methods of control theory are applied to the problem of control of fluid flow. Part III: direct numerical simulation is performed to analyze turbulent flow over longitudinal riblets, and to educe the mechanism of drag reduction by riblets. TF-55 'Turbulent Drag Reduction: Studies of Feedback Control and Flow Over Riblets' by Haecheon Choi, Parviz Moin and John Kim.... Turbulent drag reduction, Feedback control, Passive control (Riblet).