CATALOG DATA:
Passive, active and reactive flow management strategies to achieve transition delay/advance, separation control, mixing augmentation, drag reduction, lift enhancement, and noise suppression. Unified framework for flow control. Futuristic reactive control methods using MEMS devices, soft computing, and dynamical systems theory.TEXTBOOKS:
Gad-el-Hak, M., Flow Control: Passive, Active and Reactive Flow Management, Cambridge University Press, London, United Kingdom 2000.
Gad-el-Hak, M., Pollard, A., and Bonnet, J.-P., (editors), Flow Control: Fundamentals and Practices, Springer-Verlag, Berlin 1998.Prerequisites:
AME 538Topics:
The course will cover a variety of topics in the broad area of flow control. In lieu of homework and examinations, a single, multi-task research project will be assigned. The project will span the entire semester and will require both analytical and numerical work.
The ability to actively or passively manipulate a flow field to effect a desired change is of immense technological importance. In this course, methods of control to achieve transition delay, separation postponement, lift enhancement, drag reduction, turbulence augmentation and noise suppression are considered. Emphasis is placed on external wall-bounded flows, although applicability of some of the methods used for internal flows as well as for free-shear flows will be discussed. An attempt is made to present a unified view of the means by which different methods of control achieve a variety of end results. Vorticity considerations are applied to explain many of the flow control techniques examined in this course. Performance penalties associated with a particular control device such as cost, complexity or tradeoff will be elaborated. Potentially revolutionary reactive control systems that utilize the emerging technology of microfabrication and science of chaos control will be covered.
A major theme running through this course is the ability to suppress, or tame, turbulence. Despite over a century of intensive research, turbulence remains largely an enigma, analytically unapproachable yet practically very important. Consistent with the unattainability of rational, analytical solutions to turbulent flow problems and with the difficulties of physical and numerical experiments at high Reynolds numbers, controlling a practical turbulent flow to achieve a desired effect is a very difficult task. Passive control methods÷while always preferable due to their simplicity and lack of energy expenditure÷are limited in their utility by the problem practical constrains. Brute force suppression, or taming, of turbulence via active, energy-consuming control strategies is always possible, but the penalty for doing so often exceeds any potential savings. The challenge is to achieve a desired effect with minimum energy expenditure.
Spurred by the recent developments in chaos control, microfabrication and neural networks, reactive control of turbulent flows is now in the realm of the possible for future practical devices. Such control strategies are envisioned to target specific coherent structures (which are omnipresent in all turbulent shear flows), to employ arrays of microsensors/microactuators, and to exercise minimized cost functions. Other less complex control schemes, passive as well as active, are more market ready and are also witnessing resurgence of interest.
ABET category content as estimated by faculty member who prepared the course description:
Engineering Science: 3.0 credits or 100%
Engineering Design: 0.0 creditsPrepared by: Professor Mohamed Gad-el-Hak
Last Update: January 1, 2000
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