Results 1  10
of
255
Aerodynamic design via control theory
 Journal of Scientific Computing
, 1988
"... wing design; optimization. flow; inverse I. INTRODUCTION AND HISTORICAL SURVEY Computers have had a twofold impact on the science of aerodynamics. On the one hand numerical simulation may be used to gain new insights into the physics of complex flows. On the other hand computational methods can be u ..."
Abstract

Cited by 202 (62 self)
 Add to MetaCart
wing design; optimization. flow; inverse I. INTRODUCTION AND HISTORICAL SURVEY Computers have had a twofold impact on the science of aerodynamics. On the one hand numerical simulation may be used to gain new insights into the physics of complex flows. On the other hand computational methods can be used by engineers to predict the aerodynamic characteristics of
Optimum aerodynamic design using the NavierStokes equations
 Theoretical and Computational Fluid Dynamics
, 1998
"... The ultimate success of an aircraft design depends on the resolution of complex multidisciplinary tradeo s between factors such as aerodynamic eciency, structural weight, stability and control, and ..."
Abstract

Cited by 106 (45 self)
 Add to MetaCart
The ultimate success of an aircraft design depends on the resolution of complex multidisciplinary tradeo s between factors such as aerodynamic eciency, structural weight, stability and control, and
Unified Notation for Data Assimilation: Operational, Sequential and Variational
, 1997
"... The need for unified notation in atmospheric and oceanic data assimilation arises from the field's rapid theoretical expansion and the desire to translate it into practical applications. Selfconsistent notation is proposed that bridges sequential and variational methods, on the one hand, and operat ..."
Abstract

Cited by 91 (8 self)
 Add to MetaCart
The need for unified notation in atmospheric and oceanic data assimilation arises from the field's rapid theoretical expansion and the desire to translate it into practical applications. Selfconsistent notation is proposed that bridges sequential and variational methods, on the one hand, and operational usage, on the other. Over various other mottoes for this risky endeavor, the authors selected: "When I use a word," Humpty Dumpty said, in rather a scornful voice tone, "it means just what I choose it to mean  neither more nor less." Lewis Carroll, 1871. 1 J. Met. Soc. Japan, Special Issue on "Data Assimilation in Meteorology and Oceanography: Theory and Practice." Vol. 75, No. 1B, pp. 181189, 1997. 2 Corresponding author. 3 Current affiliation: CNES, 2, place Maurice Quentin, 75039 Paris Cedex 01, France. 1 J. Met. Soc. Japan, (1997), K. Ide, P. Courtier, M. Ghil and A.C. Lorenc 2 1. Introduction and motivation Modelbased assimilation of observations, or data assimilati...
Fluid Control Using the Adjoint Method
 ACM TRANS. GRAPH. (SIGGRAPH PROC
, 2004
"... We describe a novel method for controlling physicsbased fluid simulations through gradientbased nonlinear optimization. Using a technique known as the adjoint method, derivatives can be computed efficiently, even for large 3D simulations with millions of control parameters. In addition, we introdu ..."
Abstract

Cited by 70 (1 self)
 Add to MetaCart
We describe a novel method for controlling physicsbased fluid simulations through gradientbased nonlinear optimization. Using a technique known as the adjoint method, derivatives can be computed efficiently, even for large 3D simulations with millions of control parameters. In addition, we introduce the first method for the full control of freesurface liquids. We show how to compute adjoint derivatives through each step of the simulation, including the fast marching algorithm, and describe a new set of control parameters specifically designed for liquids.
Infinitedimensional linear systems with unbounded control and observation: A functional analytic approach
 Transactions of the American Mathematical Society
, 1987
"... ABSTRACT. The object of this paper is to develop a unifying framework for the functional analytic representation of infinite dimensional linear systems with unbounded input and output operators. On the basis of the general approach new results are derived on the wellposedness of feedback systems and ..."
Abstract

Cited by 59 (1 self)
 Add to MetaCart
ABSTRACT. The object of this paper is to develop a unifying framework for the functional analytic representation of infinite dimensional linear systems with unbounded input and output operators. On the basis of the general approach new results are derived on the wellposedness of feedback systems and on the linear quadratic control problem. The implications of the theory for large classes of functional and partial differential equations are discussed in detail. 1. Introduction. For
Optimum aerodynamic design using CFD and control theory. AIAA paper 951729
 AIAA 12th Computational Fluid Dynamics Conference
, 1995
"... This paper describes the implementation of optimization techniques based on control theory for airfoil and wing design. The theory is applied to a system defined by the partial differential equations of the flow, with control by the boundary as a free surface. The Frechet derivative of the cost func ..."
Abstract

Cited by 43 (24 self)
 Add to MetaCart
This paper describes the implementation of optimization techniques based on control theory for airfoil and wing design. The theory is applied to a system defined by the partial differential equations of the flow, with control by the boundary as a free surface. The Frechet derivative of the cost function is determined via the solution of an adjoint partial differential equation, and the boundary shape is then modified in a direction of descent. This process is repeated until an optimum solution is approached. Each design cycle requires the numerical solution of both the flow and the adjoint equations, leading to a computational cost roughly equal to the cost of two flow solutions. The cost is kept low by using multigrid techniques, which yield a sufficiently accurate solution in about 15 iterations. Satisfactory designs are usually obtained with 1020 design cycles. 1 The Design Problem as a Control Problem Aerodynamic design has traditionally been carried out on a cut and try basis, with the aerodynamic expertise of the designer guiding the selection of each shape modification. Although considerable gains in aerodynamic performance have been achieved by this approach, continued improvement will most probably be much more difficult to attain. The subtlety and complexity of fluid flow is such that it is unlikely that repeated trials in an interactive analysis and design procedure can lead to a truly optimum design. Automatic design techniques are therefore needed in order to fully realize the potential improvements in aerodynamic efficiency. The simplest approach to optimization is to define the geometry through a set of design parameters, which may, for example, be the weights ai applied to a set of shape functions bi(x) so that the shape is represented as Then a cost function I is selected which might, for example, be the drag coefficient or the lift to drag ratio, and I is regarded as a function of the parameters ai. The sensitivities 5 may now be estimated by making
A Perspective on Computational Algorithms for Aerodynamic Analysis and Design
 Progress in Aerospace Sciences
, 2001
"... This paper exam nes the use of computational fluid dynamics as a tool for aircraft design. It addresses the requirements for effective industrial use, and tradeoffs between modeling accuracy and computational costs. Essential elements of algorithm design are discussed in detail, together with a uni ..."
Abstract

Cited by 36 (19 self)
 Add to MetaCart
This paper exam nes the use of computational fluid dynamics as a tool for aircraft design. It addresses the requirements for effective industrial use, and tradeoffs between modeling accuracy and computational costs. Essential elements of algorithm design are discussed in detail, together with a unified approach to the design of shock capturing schemes. Finally, the paper discusses the use of techniques drawn from control theory to determine optimal aerodynamic shapes. In the future multidisciplinary analysis and optimization should be combined to take account of the tradeoffs in the overall performance of the complete system
Distributed control of spatially invariant systems
 IEEE Transactions on Automatic Control
, 2002
"... Abstract—We consider distributed parameter systems where the underlying dynamics are spatially invariant, and where the controls and measurements are spatially distributed. These systems arise in many applications such as the control of vehicular platoons, flow control, microelectromechanical system ..."
Abstract

Cited by 33 (0 self)
 Add to MetaCart
Abstract—We consider distributed parameter systems where the underlying dynamics are spatially invariant, and where the controls and measurements are spatially distributed. These systems arise in many applications such as the control of vehicular platoons, flow control, microelectromechanical systems (MEMS), smart structures, and systems described by partial differential equations with constant coefficients and distributed controls and measurements. For fully actuated distributed control problems involving quadratic criteria such as linear quadratic regulator (LQR), P and, optimal controllers can be obtained by solving a parameterized family of standard finitedimensional problems. We show that optimal controllers have an inherent degree of decentralization, and this provides a practical distributed controller architecture. We also prove a general result that applies to partially distributed control and a variety of performance criteria, stating that optimal controllers inherit the spatial invariance structure of the plant. Connections of this work to that on systems over rings, and systems with dynamical symmetries are discussed. Index Terms—Distributed control, infinitedimensional systems, optimal control, robust control, spatially invariant systems.
Computational aerodynamics for aircraft design
 Science
, 1989
"... This article outlines some of the principal issues in the development of numerical methods for the prediction of flows over aircraft and their use in the design process. These include the choice of an appropriate mathematical model, the design of shockcapturing algorithms, the treatment of complex ..."
Abstract

Cited by 27 (24 self)
 Add to MetaCart
This article outlines some of the principal issues in the development of numerical methods for the prediction of flows over aircraft and their use in the design process. These include the choice of an appropriate mathematical model, the design of shockcapturing algorithms, the treatment of complex geometric configurations, and shape modifications to optimize the aerodynamic performance. While computational methods for simulating fluid flow have by now penetrated a broad variety of fields, including ship design, car design, studies of oil recovery, oceanography, meteorology, and astrophysics, they have assumed a dominant role in aeronautical science. In the aircraft industry there is often a very narrow margin between success and failure. In the past two decades the development of new commercial aircraft successful enough to make a profit for the manufacturer has proved an elusive goal. The economics of aircraft operation are such that even a small improvement in efficiency can translate into substantial savings in operational costs. Therefore, the operating efficiency of an airplane is a major consideration for potential buyers. This provides manufacturers with a compelling incentive to design more efficient aircraft. One route toward this goal is more precise aerodynamic design with the aid of computational simulation. In particular it is possible to attempt predictions in the transonic flow regime that is dominated by nonlinear