Download or read book Gradient based Aerodynamic Shape Optimization Using ADI Method for Large scale Problems written by Mohagna J. Pandya and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aerodynamic Gradient based Optimization Using Computational Fluid Dynamics and Discrete Sensitivities for Practical Problems written by Mohagna Jayendrarai Pandya and published by . This book was released on 1997 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vector and Parallel Processing VECPAR 96 written by Jack Dongarra and published by Springer Science & Business Media. This book was released on 1997-04-09 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes a carefully arranged selection of revised full papers chosen from the presentations given at the Second International Conference on Vector and Parallel Processing - Systems and Applications, VECPAR'96, held in Porto, Portugal, in September 1996. Besides 10 invited papers by internationally leading experts, 17 papers were accepted from the submitted conference papers for inclusion in this documentation following a second round of refereeing. A broad spectrum of topics and applications for which parallelism contributes to progress is covered, among them parallel linear algebra, computational fluid dynamics, data parallelism, implementational issues, optimization, finite element computations, simulation, and visualisation.

Download or read book The Variational Method for Aerodynamic Optimization Using the Navier Stokes Equations written by and published by . This book was released on 1997 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the formulation of an aerodynamic shape design methodology using a compressible viscous flow model based on the Reynolds Averaged Navier Stokes equations. The aerodynamic shape is described by a set of geometrical design variables. The design problem is formulated as an optimization problem stated in terms of an aerodynamic objective functional which has to be minimized. The design scheme employs a gradient based optimization algorithm in order to obtain the optimum values of the design variables. The gradient of the aerodynamic functional with respect to the design variables is computed by means of the variational method, which requires the solution of an adjoint problem. The formulation of the adjoint problem is described which leads to a set of adjoint equations and boundary conditions. Using the flow variables and the adjoint variables, an expression for the gradient has been constructed. Computational results are presented for an inverse problem of an airfoil. It will be shown that, starting from an initial geometry of the NACA 0012 airfoil, the target pressure distribution and geometry of a best fit of the RAE 2822 airfoil in a transonic flow condition has been reconstructed successfully.

Download or read book Aerodynamic Optimization Using High fidelity Computational Fluid Dynamics written by Hamidreza Karbasian and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, we demonstrate the ability to perform large-scale PDE-constrained optimizations using Large Eddy Simulation (LES). We first outline the challenges associated with performing gradient-based optimization using LES, specifically chaotic divergence of the sensitivity functions. We then demonstrate that shape optimization using LES and Mesh Adaptive Direct Search Method (MADS) is feasible for aerodynamic design. Next, we introduce a Dynamic Polynomial Approximation (DPA) procedure, which allows the high-order solution polynomial representation used by the flow solver to be increased, or decreased, depending on the poll size being used by MADS. This allows rapid convergence towards the optimal design space using lower-fidelity simulations, followed by an automatic transition to higher-fidelity simulations when close to the optimal design point. Additionally, this study proposes a new physics-constrained data-driven approach for sensitivity analysis and uncertainty quantification of large-scale chaotic dynamical systems. Unlike conventional sensitivity analysis, the proposed approach can manipulate the unsteady sensitivity function (i.e., tangent) for PDE-constrained optimizations. In this new approach, high-dimensional governing equations from physical space are transformed into an unphysical space (i.e., Hilbert space) to develop a closure model in the form of a Reduced-Order Model (ROM). Afterward, a new data sampling approach is proposed to build a data-driven approach for this framework. To compute sensitivities, Least-Squares Shadowing (LSS) minimization is applied to the ROM. It is shown that the proposed approach can capture sensitivities for large-scale chaotic dynamical systems, where Finite Difference (FD) approximations fail. Therefore, we expect that implementing the proposed optimization approach can be applied to large-scale chaotic problems, such as turbulent flows, and this approach significantly reduces computational cost and data storage requirements.

Download or read book Large scale shape optimization written by Carlos E. Orozco and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Fluids Engineering written by and published by . This book was released on 1998 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation driven Aerodynamic Design Using Variable fidelity Models written by Leifur Leifsson and published by World Scientific. This book was released on 2015-01-09 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer simulations is a fundamental tool of the design process in many engineering disciplines including aerospace engineering. However, although high-fidelity numerical models are accurate, they can be computationally expensive with evaluation time for a single design as long as hours, days or even weeks. Simulation-driven design using conventional optimization techniques may be therefore prohibitive.This book explores the alternative: performing computationally efficient design using surrogate-based optimization, where the high-fidelity model is replaced by its computationally cheap but still reasonably accurate representation: a surrogate. The emphasis is on physics-based surrogates. Application-wise, the focus is on aerodynamics and the methods and techniques described in the book are demonstrated using aerodynamic shape optimization cases. Applications in other engineering fields are also demonstrated.State-of-the-art techniques and a depth of coverage never published before make this a unique and essential book for all researchers working in aerospace and other engineering areas and dealing with optimization, computationally expensive design problems, and simulation-driven design.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 34th Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 1996 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Surrogate based Global Optimization to Aerodynamic Design written by Emiliano Iuliano and published by Springer. This book was released on 2015-10-05 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic design, like many other engineering applications, is increasingly relying on computational power. The growing need for multi-disciplinarity and high fidelity in design optimization for industrial applications requires a huge number of repeated simulations in order to find an optimal design candidate. The main drawback is that each simulation can be computationally expensive – this becomes an even bigger issue when used within parametric studies, automated search or optimization loops, which typically may require thousands of analysis evaluations. The core issue of a design-optimization problem is the search process involved. However, when facing complex problems, the high-dimensionality of the design space and the high-multi-modality of the target functions cannot be tackled with standard techniques. In recent years, global optimization using meta-models has been widely applied to design exploration in order to rapidly investigate the design space and find sub-optimal solutions. Indeed, surrogate and reduced-order models can provide a valuable alternative at a much lower computational cost. In this context, this volume offers advanced surrogate modeling applications and optimization techniques featuring reasonable computational resources. It also discusses basic theory concepts and their application to aerodynamic design cases. It is aimed at researchers and engineers who deal with complex aerodynamic design problems on a daily basis and employ expensive simulations to solve them.

Download or read book A Numerical Methodology for Aerodynamic Shape Optimization in Turbulent Flow Enabling Large Geometric Variation written by Lana Osusky and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aerodynamic Shape Optimization Using Control Theory written by James John Reuther and published by . This book was released on 1996 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Aerodynamic shape design has long persisted as a difficult scientific challenge due [sic] its highly nonlinear flow physics and daunting geometric complexity. However, with the emergence of Computational Fluid Dynamics (CFD) it has become possible to make accurate predictions of flows which are not dominated by viscous effects. It is thus worthwhile to explore the extension of CFD methods for flow analysis to the treatment of aerodynamic shape design. Two new aerodynamic shape design methods are developed which combine existing CFD technology, optimal control theory, and numerical optimization techniques. Flow analysis methods for the potential flow equation and the Euler equations form the basis of the two respective design methods. In each case, optimal control theory is used to derive the adjoint differential equations, the solution of which provides the necessary gradient information to a numerical optimization method much more efficiently then [sic] by conventional finite differencing. Each technique uses a quasi-Newton numerical optimization algorithm to drive an aerodynamic objective function toward a minimum. An analytic grid perturbation method is developed to modify body fitted meshes to accommodate shape changes during the design process. Both Hicks-Henne perturbation functions and B-spline control points are explored as suitable design variables. The new methods prove to be computationally efficient and robust, and can be used for practical airfoil design including geometric and aerodynamic constraints. Objective functions are chosen to allow both inverse design to a target pressure distribution and wave drag minimization. Several design cases are presented for each method illustrating its practicality and efficiency. These include non-lifting and lifting airfoils operating at both subsonic and transonic conditions."

Download or read book A Preconditioning Method for Shape Optimization Governed by the Euler Equations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-09 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: We consider a classical aerodynamic shape optimization problem subject to the compressible Euler flow equations. The gradient of the cost functional with respect to the shape variables is derived with the adjoint method at the continuous level. The Hessian (second order derivative of the cost functional with respect to the shape variables) is approximated also at the continuous level, as first introduced by Arian and Ta'asan (1996). The approximation of the Hessian is used to approximate the Newton step which is essential to accelerate the numerical solution of the optimization problem. The design space is discretized in the maximum dimension, i.e., the location of each point on the intersection of the computational mesh with the airfoil is taken to be an independent design variable. We give numerical examples for 86 design variables in two different flow speeds and achieve an order of magnitude reduction in the cost functional at a computational effort of a full solution of the analysis partial differential equation (PDE). Arian, Eyal and Vatsa, Veer N. Langley Research Center NASA/CR-1998-206926, NAS 1.26:206926, ICASE-98-14 NAS1-19480; RTOP 505-90-52-01...

Download or read book Analysis of the Hessian for Aerodynamic Optimization written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-30 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we analyze inviscid aerodynamic shape optimization problems governed by the full potential and the Euler equations in two and three dimensions. The analysis indicates that minimization of pressure dependent cost functions results in Hessians whose eigenvalue distributions are identical for the full potential and the Euler equations. However the optimization problems in two and three dimensions are inherently different. While the two dimensional optimization problems are well-posed the three dimensional ones are ill-posed. Oscillations in the shape up to the smallest scale allowed by the design space can develop in the direction perpendicular to the flow, implying that a regularization is required. A natural choice of such a regularization is derived. The analysis also gives an estimate of the Hessian's condition number which implies that the problems at hand are ill-conditioned. Infinite dimensional approximations for the Hessians are constructed and preconditioners for gradient based methods are derived from these approximate Hessians. Arian, Eyal and Ta'asan, Shlomo Ames Research Center NAS1-19480...

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Global Optimization Algorithms for Aerodynamic Design written by Oleg Chernukhin and published by . This book was released on 2011 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on an investigation of multi-modality in typical aerodynamic shape optimization problems and development of optimization algorithms that can find a global optimum. First, a classification of problems based on the degree of multi-modality is introduced. Then, two optimization algorithms are described that can find a global optimum in a computationally efficient manner: a gradient-based multi-start Sobol algorithm, and a hybrid optimization algorithm. Two additional algorithms are considered as well: a gradient-based optimizer and a genetic algorithm. Finally, we consider a set of typical aerodynamic shape optimization problems. In each problem, the primary objectives are to classify the problem according to the degree of multi-modality, and to select the preferred optimization algorithm for the problem. We find that typical two-dimensional airfoil shape optimization problems are unimodal. Three-dimensional shape optimization problems may contain local optima. In these problems, the gradient-based multi-start Sobol algorithm is the most efficient algorithm.