598 research outputs found
A semi-smooth Newton method for regularized state-constrained optimal control of the Navier-Stokes equations
Revised version of the preprint first published 01. September 2005 under the title "A semi-smooth Newton method for state-constrained optimal control of the Navier-Stokes equations"In this paper we study semi-smooth Newton methods for the numerical solution of pointwise state-constrained optimal control problems governed by the Navier-Stokes equations. After deriving an appropriate optimality system, a class of regularized problems is introduced and the convergence of their solutions to the original optimal one is proved. For each regularized problem a semi-smooth Newton method is applied and its convergence verified. Finally, selected numerical results illustrate the behavior of the method and a comparison between the - and the Fischer-Burmeister as complementarity functionals is carried out
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Mini-Workshop: Control of Free Boundaries
The field of the mathematical and numerical analysis of systems of nonlinear pdes involving interfaces and free boundaries is a burgeoning area of research. Many such systems arise from mathematical models in material science and fluid dynamics such as phase separation in alloys, crystal growth, dynamics of multiphase fluids and epitaxial growth. In applications of these mathematical models, suitable performance indices and appropriat
POD model order reduction with space-adapted snapshots for incompressible flows
We consider model order reduction based on proper orthogonal decomposition
(POD) for unsteady incompressible Navier-Stokes problems, assuming that the
snapshots are given by spatially adapted finite element solutions. We propose
two approaches of deriving stable POD-Galerkin reduced-order models for this
context. In the first approach, the pressure term and the continuity equation
are eliminated by imposing a weak incompressibility constraint with respect to
a pressure reference space. In the second approach, we derive an inf-sup stable
velocity-pressure reduced-order model by enriching the velocity reduced space
with supremizers computed on a velocity reference space. For problems with
inhomogeneous Dirichlet conditions, we show how suitable lifting functions can
be obtained from standard adaptive finite element computations. We provide a
numerical comparison of the considered methods for a regularized lid-driven
cavity problem
Existence of optimal boundary control for the Navier-Stokes equations with mixed boundary conditions
Variational approaches have been used successfully as a strategy to take
advantage from real data measurements. In several applications, this approach
gives a means to increase the accuracy of numerical simulations. In the
particular case of fluid dynamics, it leads to optimal control problems with
non standard cost functionals which, when constraint to the Navier-Stokes
equations, require a non-standard theoretical frame to ensure the existence of
solution. In this work, we prove the existence of solution for a class of such
type of optimal control problems. Before doing that, we ensure the existence
and uniqueness of solution for the 3D stationary Navier-Stokes equations, with
mixed-boundary conditions, a particular type of boundary conditions very common
in applications to biomedical problems
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Numerical Techniques for Optimization Problems with PDE Constraints
The development, analysis and implementation of efficient and robust numerical techniques for optimization problems associated with partial differential equations (PDEs) is of utmost importance for the optimal control of processes and the optimal design of structures and systems in modern technology. The successful realization of such techniques invokes a wide variety of challenging mathematical tasks and thus requires the application of adequate methodologies from various mathematical disciplines. During recent years, significant progress has been made in PDE constrained optimization both concerning optimization in function space according to the paradigm ’Optimize first, then discretize’ and with regard to the fast and reliable solution of the large-scale problems that typically arise from discretizations of the optimality conditions. The contributions at this Oberwolfach workshop impressively reflected the progress made in the field. In particular, new insights have been gained in the analysis of optimal control problems for PDEs that have led to vastly improved numerical solution methods. Likewise, breakthroughs have been made in the optimal design of structures and systems, for instance, by the socalled ’all-at-once’ approach featuring simultaneous optimization and solution of the underlying PDEs. Finally, new methodologies have been developed for the design of innovative materials and the identification of parameters in multi-scale physical and physiological processes
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Optimal Control of Coupled Systems of PDE
The Workshop Optimal Control of Coupled Systems of PDE was held from April 17th – April 23rd, 2005 in the Mathematisches Forschungsinstitut Oberwolfach. The scientific program covered various topics such as controllability, feedback control, optimality conditions,analysis and control of Navier-Stokes equations, model reduction of large systems, optimal shape design, and applications in crystal growth, chemical reactions and aviation
Optimal control of the stationary Navier-Stokes equations with mixed control-state constraints
Revised version of the preprint first published 06. December 2005In this paper we consider the distributed optimal control of the Navier-Stokes equations in presence of pointwise mixed control-state constraints. After deriving a first order necessary condition, the regularity of the mixed constraint multiplier is investigated. Second-order sufficient optimality conditions are studied as well. In the last part of the paper, a semi-smooth Newton method is applied for the numerical solution of the control problem. The convergence of the method is proved and numerical experiments are carried out
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Mini-Workshop: Numerical Analysis for Non-Smooth PDE-Constrained Optimal Control Problems
This mini-workshop brought together leading experts working on various aspects of numerical analysis for optimal control problems with nonsmoothness. Fifteen extended abstracts summarize the presentations at this mini-workshop
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