Journal ArticleDOI
Application of neural networks to turbulence control for drag reduction
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In this article, a new adaptive controller based on a neural network was constructed and applied to turbulent channel flow for drag reduction, which employed blowing and suction at the wall based only on the wall-shear stresses in the spanwise direction.Abstract:
A new adaptive controller based on a neural network was constructed and applied to turbulent channel flow for drag reduction. A simple control network, which employs blowing and suction at the wall based only on the wall-shear stresses in the spanwise direction, was shown to reduce the skin friction by as much as 20% in direct numerical simulations of a low-Reynolds number turbulent channel flow. Also, a stable pattern was observed in the distribution of weights associated with the neural network. This allowed us to derive a simple control scheme that produced the same amount of drag reduction. This simple control scheme generates optimum wall blowing and suction proportional to a local sum of the wall-shear stress in the spanwise direction. The distribution of corresponding weights is simple and localized, thus making real implementation relatively easy. Turbulence characteristics and relevant practical issues are also discussed.read more
Citations
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The MEMS Handbook
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References
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Journal ArticleDOI
Turbulence statistics in fully developed channel flow at low reynolds number
TL;DR: In this article, a direct numerical simulation of a turbulent channel flow is performed, where the unsteady Navier-Stokes equations are solved numerically at a Reynolds number of 3300, based on the mean centerline velocity and channel half-width, with about 4 million grid points.
Journal ArticleDOI
Active turbulence control for drag reduction in wall-bounded flows
TL;DR: In this article, the authors explore concepts for active control of turbulent boundary layers leading to skin-friction reduction using the direct numerical simulation technique and show that significant drag reduction is achieved when the surface boundary condition is modified to suppress the dynamically significant coherent structures present in the wall region.
Proceedings ArticleDOI
Adaptive inverse control
Bernard Widrow,Michel Bilello +1 more
TL;DR: In this paper, a method for adaptive control of plant dynamics and for controlling plant disturbance for unknown linear plants using neural networks is described. But this method is not suitable for control of nonlinear plants.
Journal ArticleDOI
On the dynamics of near-wall turbulence
TL;DR: A model of the dynamic physical processes that occur in the near-wall region of a turbulent flow at high Reynolds numbers is described in this paper, where the hairpin vortex is postulated to be the basic flow structure of the turbulent boundary layer.
Journal ArticleDOI
Feedback control for unsteady flow and its application to the stochastic Burgers equation
TL;DR: In this article, the authors apply mathematical methods of control theory to the problem of control of fluid flow with the long-range objective of developing effective methods for the control of turbulent flows.